David Wilson knows more about 4WD than probably anyone else on the planet. If you’ve got a question about the fit-out of your vehicle, a driving technique or even help with new vehicle selection, put him to the test! Ask Dave a 4WD question!
I went on your Moreton Island trip Saturday 16th January. I think you mentioned Toyo tyres LT265/65R17 121S was your preferred rubber to sharpen up the steering and handling on DMAX. Is this the right spec for the tyre you like? I know you have the 70R17 on your vehicle but i don’t want to void the warranty so will stick with the 65 for the time being.
Wow this response is a pretty late… sorry!
Was going back over old correspondence so please accept my apologies at overlooking it at the time.
I reckon you have made your purchase in the meantime and yes you were right the “65” will serve you faithfully.
Let us know your reactions to the Toyo, most people comment on how much sharper the steering is and how much better they go around corners.
Happy New Year.
Both my wife and I attended a 4wd course last year and during the theory presentation evening you suggested two brand of tyres.
Bridgestone and Toyo.
I am interested in updating tyres on my Pathfinder and I would be interested in your thoughts to which tyres I fit.
At present I have Sumitomo Tour Plus LXT 265/65R17 112T M+S fitted which give an extremely hard ride.
What Bridgestone replacement would you recommend?
I would say I am a 50/50 user both bitumen and dirt.
Your advice would be really appreciated.
Good to be hearing from you once more.
That Sumitomo you have currently is a Passenger car tyre and not very strong. The size is OK but I’d be recommending a Toyo OPAT2 all-terrain based on recent experience driving a number of Isuzu DMAX utes and MUX wagons as we use those on the I-Venture Club cars around the country with really good results. The difference with what I’m recommending you is this one is Light-Truck construction and more durable without a harsh ride. It’ll end up being LT265/65R17 120R.
I’m in the wilds of Coffin Bay at the moment and carrying with me one of our hire Kimberley camper trailers fully loaded and the Toyos on my DMAX haven’t put a foot wrong thus far, pumped up at 32/36psi whilst towing on the highway or down to 15/15psi in the sands.
Locally to replace them I’d suggest Darryl at Tyrepower Blackwood in the south or Anthony at BSelect Windsor Gardens in the north. They are our preferred suppliers and really look after my clients. Sorry I haven’t got their phone numbers handy, but you’ll be able to find them on the net I’m sure.
Let me know how you go.
Thanks for your very quick and informative response to my scary aquaplaning experience. I will follow up on your suspension and tyre recommendations.
Just a couple of thoughts I would appreciate your opinion on:
- The Toyota dealership advised me to run 40psi in the Dunlop Grandtrek tyres. Is that too high in your opinion as it will be a few months before I make the change to Toyo as per your recommendation?
- It has been suggested to me that the semi transport passing me at the time would have had a sucking effect combined with the water on the road thereby accentuating the aquaplaning problem?
Ha, that’s priceless and shows just how little they understand about their own vehicles! 40psi/275kPa is 38% over-inflated when compared to the vehicle’s tyre placard and even if I refer to the fount of tyre knowledge, the only bit of science written for tyres and the very same publication used by manufacturers in determining the placard’s content, “The Tyre and Rim Association Manual”, it states an absolute maximum of 36psi/250kPa for a 265/65R17 112S.
40psi/275kPa will only make your problem worse with nervous steering, lots of bump reaction off the road surface and prematurely worn out tyres with increased puncture risk AND extended braking distances!!!
Re the semi going by, yes there can be some buffeting as the turbulence generated by the truck upsets the air you’re driving through and could well have been a contributor, so that comment has some merit, but I believe the other factors I’ve mentioned are the ones that need exploring.
I’ve had a chat with a client who also runs a 150 Prado and has made the changes to his vehicle that I’m recommending and he’d made the comment over and over again about just how bad the Prado is in standard trim and how much better it is once changed. He tows too. I think there’s merit in pursuing this because you’ve already got a lot invested.
If you want to talk to someone at ARB re the suspension ask for Steve Gull at ARB Regency Park, phone 8244 5001.
Re Toyo Tyres you’ll be able to get some pricing from Tyrepower at Blackwood, call Darryl Crouch 8370 2195, or on this side of town Anthony Gliessert at BSelect Windsor Gardens on 8369 1045.
We have a 150 series GXL Prado stock standard except for air bags to assist towing. We have an Avan Frances caravan fitted with adventure pack, also stock standard. Avan told us not to use stabilisers or we would void our warranty and we only needed air bags on the prado.
The van weighs about 2.1t fully loaded and has single axle with 135 kg ball weight. With about 12psi in the air bags it seems to tow fairly well when correctly loaded. However we experienced aquaplaning for a brief couple of seconds just as a semi-trailer was passing and it could have been a real unexpected disaster.
There was less than 6inches of water on the passenger wheel side of the bitumen road.
Do you have any suggestions that could eliminate this fear in the future as we were only doing about 85 to 90 km/h at the time due to rain.
Geoffrey K. 11/11/15
Wow that didn’t sound like a whole lot of fun.
Towing is a pretty tricky subject and getting the setup right can be a process of elimination.
Look there’s a few things I can identify:
Firstly the Prados rated towing ability is a paltry 2,500kgs and with your caravan weighing in at 2,100kgs GVM the Prado is uncomfortably close to the limit
Standard suspension and tyres will have influenced your near-miss. In our experience (and it doesn’t matter who the maker is) stock springs and tyres are crap for anything other than ferrying passengers around the city (where 90% of 4WD sales go these days). If you have any aspirations for travel, as you’re indicating, you’ll need to make some changes to the car
Whilst we’re talking about suspension let’s talk about your airbags. I don’t like them at all. The concept may work on heavy transport but my experience with light vehicles is that it doesn’t often translate successfully. The problem is that it is a band-aid solution, trying to compensate for a spring that is too soft in the first place. With an inflated bag in place the suspension can’t work through its full height (articulation) as it’s restricted, therefore the spring can’t absorb anything much more than its initial flex, bigger undulations in the road surface result in bump-steer as the suspension hits its limit much sooner (what would have been the chassis-mounted rubber bump stop) with the inflated bag in the way. The bump-steer phenomenon as the suspension crashes to its now artificially impeded stop translates often into a steering reaction and a vehicle may change direction even though the driver hasn’t made any deflection via the steering wheel. The other consequence of air-bags in the longer term are drivers reporting chassis cracks and failure, again caused by the suspension coming to a stop prematurely and passing all that load into the chassis rails instead of it being dissipated by the spring
We’ll recommend to any of my clients who intend towing to replace the suspension outright, front and rear, to end up with something more precise and able to deal with any or no load. We’ve always used ARB’s Old Man Emu kits as they are very, very good. It totally transforms the vehicle’s ability and makes them safe. In our line of work we occasionally manage a holiday with one of our hire Kimberley Campers loaded up with all the gear including a boat, or we tow our tandem ATV trailer, or our enclosed ATV trailer, or the tandem Bobcat trailer. The load range across those four is 1,200 – 3,500kgs and when attached to the ute there’s barely any discernible deflection in the rear springs to indicate they are struggling AND laden or unladen the ride is still compliant!!!
If you’re on standard tyres they too will have contributed to your “moment”. The standard Dunlop Grandtreks are pathetic. The tread pattern is typically passenger car, a tight network of tread blocks and sipes that will struggle to pump water out the way. They also are very vague in their steering, wandering all over the road and requiring constant steering corrections. The other critical discussion point for me with tyres is their load index. Load index is the barometer that tells us the tyre’s true strength and I suspect yours is rated 112 = 1,120kgs. With your caravan attached the back tyres in particular will be working harder and nearer their weight limit through towball downforce. It’s much better for towing for a whole bunch of reasons to opt for a tyre of light-truck construction and one that has a minimum 120 = 1,400kgs load index. Once you hit 120 you end up with a tyre that has some durability and carrying capacity. The right tyre will last double the distance of the Grandtreks, suffer no punctures (if you manage your pressures correctly) and steer you predictably in all weathers
If you wanted to retain the standard tyre size 265/65R17, Toyo make their OPAT2 all-terrain in a LT265/65R17 120R, the 120 hits the magic mark I mentioned before. We use this product on all our vehicles now and they are brilliant! Not noisy, carry a big load, run out to 80,000kms+ with no punctures, tow and steer beautifully = perfect 4WD tyre!
Pressures. The placard on your Prado states 200kPa or 29psi (front and rear and irrespective of the load) from memory which is right for the original passenger car tyres fitted ex-factory. With the Toyos fitted you’ll follow that same recommendation unladen and bump the rears up to a likely 250kPa=36psi for the rears when towing
I hope that helps you become a little better informed as your holiday experience should be a happy one, not one tinged with fear!
Let me know what you decide and I’d recommend you do our First Time Out course to get a better picture of how your vehicle works on all road surfaces http://adventure4wd.com.au/courses/recreational-4wd-training/first-time-out-15-days-duration
I was on the I-Venture course 21 Nov 15. Thank you for the awesome day, my wife and I really enjoyed our introduction to the 4WD world.
We were inspired to give this a go and may have found a new past time.
I was wondering if you could e-mail a list of modification your Adventure Isuzu had and where you had it modified.
In particular the tyres, suspension and that air lock transmission thingy you demonstrated and were talking about.
Lesson learnt on the day: side steps and nudge bars are just future cosmetic damage. 🙂
Shane and Carly F. 22/11/15
Sorry was supposed to reply to this weeks ago.
Here’s a pretty complete list of the A4WD truck written for 4X4 Magazine last week as they’re doing some features on us soon.
Black LS-M DMAX
ARB Old Man Emu suspension front and rear
ARB Under vehicle protection
ARB Bullbar, side-rails and steps and rear-step towbar
ARB Long Ranger fuel tank 132 litres
ARB Air-Locker and twin pump compressor with unique switchgear
ARB Reversing camera/mirror
ARB IPF driving lights
ARB Tie-down rails in ute tub sides
GME UHF in-car communications
Supa-Fit Canvas seat covers with A4WD embroidered logos
CSA Alloy Wheels, set of 17” Granites and 16” Raptors
Toyo OPAT2 all-terrains (fitted to 17” wheels), TOYO OPAT mud-terrains (fitted to 16” wheels)
HPD (High Performance Diesel) intercooler and plumbing
Rhino Linings spray-on urethane tub lining
Nissan D40 “Utilitrak” tie-down rails in tub floor
Custom A4WD dreamtime Red Belly black snake in vivid orange signage
Yep, you’re right… nudge bars and sidesteps are crap!
I have often booked our teachers to do your highly recommended courses.
I’m looking to drive around Australia in 2019.
Early next year I will be in the market to buy a 4WD.
From your experience and recommendation, what stacks up better – Prado or Nissan Patrol?
I will be buying a diesel option.
Will not be doing much off-road driving.
Will be towing a caravan.
Gavin C. 4/12/15
Good to hear from you again.
Congratulations on taking the plunge, however both vehicle choices I think have some flaws.
Firstly, Prado. Overpriced, overrated. The 4WD systems in the vehicle are very good but that’s not enough to overcome the ridiculous price and the paltry tow capacity of 2,500kgs. I’ve had a client write to me recently with a Prado and caravan combo well under that weight threshold having a moment when the vehicle became unsettled by side drafts (a passing truck) and the owner lost confidence in the vehicle. To fix that dilemma you need to spend a fair bit of money on suspension and tyres and even then you still have the legal 2,500kgs ceiling.
Secondly, Patrol. I’m assuming you’re talking about the Y61 or GU Patrol? Too big a vehicle for too small a motor. It’s a BIG vehicle, needing a big parking space around town, a fair bit of space on the road and on a track. It’s seriously dated, with basic electronic safety systems from a generation or two ago. Price is sort of keen, but not enough to win me over.
Have you tried Isuzu’s MUX? This wagon shares its underpinnings with their DMAX ute which is as tough as old boots, a 3.0L diesel truck engine with incredible fuel efficiency. Buy the auto transmission and you’ll have a great tow bus. They’re affordable too and will have good resale in the future because Isuzu’s name is king in diesel engine circles and the truck fraternity. It’s an honest toiler. Has 3,000kgs tow capacity.
The alternative would be Pajero. Mitsubishi have had a winner with this vehicle since the current shape launched back in 2003. Despite the fact it’s now 12 years old, Mitsubishi have given it regular updates. It has excellent electronics and I love their “Super-Select” 4WD system. It has 3,000kgs towing capacity so it trumps Prado easily.
Mitsubishi are also about to launch their new Pajero Sport, replacing the Challenger. This vehicle is actually a Triton ute base (all utes spawn a wagon these days), but with a wagon body style that’s bold… It’s a pretty clever machine electronically, takes the Pajero’s capability to a newer level. Price is keen too. Has a 3,100kgs tow capacity.
Have a look at those, they’ll be heaps better than your current selection.
PS Auto trans is the way to go, they’re very clever now.
After doing your first time out course we are now off to coffin bay and are looking to tackle some sand dunes! What is the best way to tackle soft sand dunes especially going up and down them. We have a 120 series prado. Apart from lowering the tire pressure and maintaining momentum, what are the key points we need to look out for when tacking sand hills and how does our approach need to be different from that of a conventional uphill or downhill on rocks.
Lucky you, that’s one of my favourite parts of the world.
Look the secret to driving over there is tyre pressure. There’s a couple of spots where people regularly get themselves into bother, namely Gunyah and Almonta Beaches, the access track into the park just past Little Yangie where there’s an influence the tide exerts on the sands and Seven Mile beach can be iffy on a high tide, so check the tides to ensure you’ve got safe ingress and egress.
Re tyre pressure I’d be going straight down to 15psi as soon as you get to Big Yangie as you’ll be on sand and limestone for the rest of the day and the tyre will now have enough flexibility to cope with the rock and stretch out long enough to give the flotation on the sand.
Remember straight steering, use of LOW range (all the gears) and smooth, fluid applications of power.
Have fun and send us a pic from somewhere on the beach!
I have a nissan navara d22 and it’s time for new tyres. stock are 265/70/16, but I want to upgrade to 265/76/16, which results in a 26mm increase in outside diameter. I have been told different stories by different tyre places as to whether this is legal in SA or not. One said 15 mm max, and the other said 50 mm max since it is a 4×4/commercial vehicle. Any idea what SA regulations really are? If its 15 mm, then there must be a lot of people out there breaking the rules! I don’t want to end up in a position where I am getting defected or not insured in the event of an accident, but I’m keen to get the bigger size in if they fit.
Thanks for your mail. Your question is one we come across regularly and one that illustrates how legalities aren’t often convenient, but commonsense will prevail in your case.
The D22 is a good ute, we’ve had an association with Nissan for ages having owned 2 x D40s in the last 6 years and we see D22s on courses regularly. The tyre size on the STR was a sensible one as it offered a reliable LT (Light Truck) replacement option, the very same LT265/75R16 you quoted below.
The difference is in the rolling diameter, your current 777mm Vs 802mm on the LT version. The attached bulletin from SAPOL states a 15mm increase is the maximum permitted without engineers certificate. The difference we’re talking here is 26mm. By the time you run them for a few months and start peeling off tread depth the numbers will start to look the same and if I wanted to be really pedantic the mere act of changing the pressures will affect the ultimate height the vehicle sits at too. From my experience substituting P (Passenger) for LT (Light Truck) in the nearest equivalent size will satisfy most jurisdictions legal requirements. Going P265/70R16 to LT265/75R16 fits comfortably within that statement as it’s only a 5% aspect ratio increase in sidewall height.
I can recommend to you the Bridgestone D697LT in that size, the LT265/75R16 123 R Desert Dueler. It’s the very same tyre we run on our D40 and they are ACE! We will clock up big kilometres (I’m expecting 80K), the steering is sharp, they stop brilliantly, have excellent puncture resistance and are quiet.
The reason we push this one is that the pattern is aggressive enough for most SA conditions and the load index is up over the 120 threshold (which we believe is the true indicator of tyre strength – a 123 load index = 1550kgs carrying capacity per tyre is likely 40-50% better than your current tyre). There’ll be others who advocate USA brands like Cooper, BFG and Mickey Thompson but personally I don’t like them. The tread patterns will likely be overly aggressive (that means loud) and in the dry and wet on bitumen they’ll be loose, off-road sure they’ll perform, but on Aussie Outback gravels the tread blocks will disintegrate and chip, chunk and cut, worn out well before their time. I’ve seen dozens of these brands destroyed because USA rubber compounds are too hard.
The only qualifier I’d put on this is that if you are still on standard suspension you might find the tyre just clips the front bumper on full turn locks left and right under compression (like on a bump). We always recommend to clients that every new 4WD will need a tyre and suspension change to make it right. Using an ARB kit in your car will make it hugely better both on and off-road and fix the clearance issue mentioned here.
I’ve seen D22s with 285s after suspension mods, but you might then be asking for trouble from the law on grossly exceeding the rolling diameters (see above). This does have implications especially for braking, handling and gearing, so don’t go down that path.
For Bridgestone sales contact Dimi or Andrew at the Bridgestone store at Wingfield 83489122 and ARB sales contact Regency Park on 82445001 (assuming you’re in SA) and tell them we sent you, it’ll help with the price.
Hope that helps.
PS Make sure that whatever selection you make the tyre is genuinely an LT (Light Truck) construction and aim for a minimum 120 load index. There’s lots of shonks out there who’ll take advantage of those who go into their stores underprepared!
Reply from Sam
Thanks for the detailed reply!
Good to hear, the Bridgestone D697LT 265/75R16 is exactly what I was looking at.
Regarding suspension, I have intention of fitting a 2″ susp lift before a trip to the Kimberley middle of next year. However, funds don’t allow for it yet and it’s time to change tyres now. Do you think I’ll get away with the bigger tyres on the standard suspension for 8 months or so. Is some slight occasional scrubbing going to be a problem? Can I remove the guards or modify them in some way?
Really appreciate your help as I seemed to get mixed answers from a lot of the ‘experts’.
Reply from David
The scrubbing issue should only be obvious on full lock turns so when you hear the scrape just unwind the steering and be prepared to do 4-5 point turns instead of 3! If you get a friend to give you a hand, stand near the front LHS and RHS guards and get the friend to turn the steering through its full arcs and watch how close the wheel gets to the front and rear lips of the wheelarches. It’s when the wheel pivots that either the inside or outside shoulders of the tyres will likely catch. Compressed suspension like on a bump will accentuate the problem.
With my son’s Subaru L series wagon we took to the guards with tinsnips and a hammer and made the necessary adjustments… brutal but effective (don’t suggest you do that though).
ARB make the most dependable suspension systems, we been using them for over 20 years.
I did your course a few years back with the SA Govt and still remember many lessons and applied them regularly. I haven’t had a 4WD for about 3 years and am now looking again but as a second car for fun and camping rather than my now needed small commute. I was wondering if you had a view on a 1997 Pajero, how they hold up these days (has 210,000km) and their performance. The one I am looking at is on gas. Is there anything I should be looking out for? (I previously had a Hilux and a Hyundai Terracan Highlander, which I loved and performed very well on Gibb River Road and Vic high country after the sand dunes of SA.
Good to be hearing from you again and good luck with the future expeditions.
Pajeros have always been one of my favourite 4WD wagons having owned a 2003 NH diesel for around 3 years. I particularly like their Super Select 4WD transmission as it offers either part-time 2WD running in the city on dry days or full-time 4WD on those wet days plus the usual off-road 4WD options in HIGH and LOW range.
From 2003 in Pajero diesel and 2005 in Pajero petrol, have been especially good as they’ve had a full suite of safety essentials in the form of ABS/ETC/VSC, well before the now federally mandated fitment (as of this year) requirement for all new vehicles sold locally. Those 3 features have the capacity to prevent 40% of casualty crashes, so they’re worth having if your budget will stretch to a younger vehicle.
I have to confess to not being a fan of petrol powered 4WDs and even if in your case LPG fitment applies, which will help in the fuel cost stakes, petrol engines just have too many drawbacks. Here’s an article I wrote on our website about why you should consider a diesel engined vehicle… http://www.adventure4wd.com.au/our-environment/why-you-should-buy-a-diesel
Here’s a summary:
- Poor fuel efficiency (in some cases a diesel can be twice as frugal)
- Petrol engines produce their maximum power/torque high in the rev range (encouraging you to use more accelerator and impact your fuel usage)
- With those higher engine speeds comes less comfortable off-road driving as you’ll have to travel too fast to maintain momentum on sand or in mud
- Higher engine speeds = more wear and tear
- Petrol engine 4WD resale value is APPALLING because no-one wants them (that might be why this vehicle you’re looking at seems appealing)
- LPG fitments can go wrong in older age requiring expensive refits and can shorten engine life
- Greater CO2 levels from the exhaust pipe
Not all diesels are exceptional though. During the last decade there’s been some massive advances. The article above mentions the acronym CRD, common-rail diesel. These are at the cutting edge of modern diesel design and are now common across all vehicle makers, but previous generations were a bit hit and miss. I’d suggest if you start looking at diesels you let me know what appeals to you (make/model) and then I can advise yah or nay. Direct-injection diesels are always better, like those seen on Holden Rodeos, than the indirect-injection diesels seen on just about every other Japanese 4WD until recently. Land Rover too used direct on their 4WDs (Defender/Discovery/Range Rover) and the promise is better fuel efficiency and torque. Toyota have been really slow off the mark, their diesels have been underpowered and indirect until the release of the “D4D” in Hilux (2005) and Prado (2009).
Have you considered utes? I personally think they are the most attractive/versatile vehicle platform and have great potential for 4WD trips. There’s plenty of them out there to choose from.
Look forward to your reply.
We did your first time out course last year.
We are heading off to the kimberly and i remember you related some information about tyre pressure and speed. As you reduce tyre pressure the maximum speed should also be reduced i remember you quoted some rough pressure/speed figures but i can’t find them in my notes. Can you email those rough figures to me when you can please
Lucky you with your pending trip.
Here’s the essence of the pressure/load/speed argument.
Start with your vehicle’s placarded pressure settings for bitumen running at city – higher speeds
When on dirt reduce your placarded pressures by 20% and slow down by 20%
When on tracks that become increasingly more difficult say for bogging potential (sand/mud) continue to reduce pressure and speed (15psi = 40kph, 18psi = 50kph, 20psi = 60kph as a rough guide)
When we operate in the Flinders on sharp and shaly rock/gravel surfaces we typically use around 20psi or less depending on the severity of the gradient or the looseness of the surface
Hope that helps, send us a pic of you and the truck from somewhere exotic!
Can you recommend any 4WD accessory manufacturer or supplier of steel plate underbody protection for a 2010 Suzuki Grand Vitara 2.4 litre petrol, 5 door vehicle.
You’ll need to get that custom built as the off-road volumes for that make/model would be extremely low.
Suggest you contact a metal fabricator in your local area.
My son has just got a Nissan Patrol 1998 – was wondering what is the largest legal tyre?
I need a bit of help. ask him to read the tyre placard on the glovebox lid of the owners manual and see what cam with the vehicle standard (i.e. it might say 265/70R16 112S or 31×10.5R15 108N or LT235/85R16 120Q), also what model is that GQ or GU and what State do you live in? You’ll see a lot of earlier Patrol owners running big suspension lift kits to put big wheels underneath for better clearance but it impacts on roadholding (they fall over more easily), brakes (they take longer to stop), wear and tear (a lot more force on components). There’s also very precise ADR requirements that permit on average across all States a maximum of 25mm increase in diameter.
We are planning on having another go at the simpson desert this July and as we sold our shared patrol last year, Dad has offered up the family 4wd (Nissan Pathfinder). I was hoping to get your advice on some additions dad has agreed to:
-OME nitrocharger suspension upgrade
-New set of 694 A/T to replace the highway terrains
-A set of bash plates from TJM
Are these the products you would recommend? Is there anything else you would suggest for a trip like this? We are planning on coming and paying you a visit soon to give you the photos you asked for and may organise the hire of a sat phone.
Thanks in advance,
Hey it’s good to hear from you again, and the Simpson trip sounds great.
The ARB OME suspension upgrade sounds like the right place to start as all stock suspension is crap. It’ll end up with the same ride height as our recent Navara, so it’ll be most welcome. I’d put the same tyres we’re running too (if its a 16″ wheel) the new Bridgestone D697 Dueler in the LT265/75R16 123R size, we’ve had them on for 2 months now and they’re superior to the old D694. Re bashplates, I’m pretty sure the bashplates that are on the Navara will fit the Pathfinder (again ARB issue), ours are doing a great job and have protected things recently in the Flinders.
Apart from a compressor and a tyre gauge, a fridge for the food and satphone for insurance, I think you’ve got it covered.
Look forward to catching you up.
I wondered if you could help clarify things for me about the weight towing of our landcruisers. If the towing capacity of the landcruiser is 3500kg braked and the kerb weight of the landcruiser is 2320kg do we subtract the kerb weight from the towing capacity to get the result max trailer weight (what about people)? If we go with the GCWR there doesn’t seem any point in upgrading our trailer brakes?
Towing capacity with trailer brakes: 3500kg
Towing capacity without brakes: 750kg
Gross Combination Weight Rating: 3300kg
Trailer weight 2200kg
Kerb Weight: 2320kg
Wow that’s a curly one for a Thursday afternoon, but here goes!
The Landcruiser traybacks you run (the V8 diesels) have a GVM (Gross Vehicle Mass) of 3300kgs. That is vehicle, fuel, accessories like bullbar/winch/towbar/side rails, cargo (including humans), everything.
Toyota say you can tow a trailer weighing up to 3,500kgs (that has brakes), and that is trailer, spare wheel(s), plus load in whatever form it comes, everything.
The GCM (Gross Combination Mass) is therefore 6,800kgs, GVM + tow mass = GCM.
The only way you’ll really know this is to get along to a weighbridge.
My only reservation is the type of brakes fitted to trailers. When we built our ATV trailer (an enclosed pop-up lid type), weight was a factor. It has aluclad sides and alloy chequerplate roof to try and keep the weight down. We fitted hydraulic over-ride disc brakes to it activated via a Treg hitch. It stops well. Some trailers we hire from time to time have simpler cable operated drum brakes… they’re crap. That might be the issue, as keeping a drum brake in good condition is a bit of an ask where dirt/sand/mud can enter the hub assembly and erode the linings. Stretched cables too don’t provide reliable braking applications, so there’s a fair bit of slop/tardiness in their reaction. When you’re right at the limit with the weights you need good suspension, good tyres, correct tyre pressures for the loads and bloody good brakes.
Hope that helped?
Thanks for the initial info on snatch straps for the Toyota Prados and Holden Captiva.
After purchasing them I looked at the recovery point for the Captiva and it’s a screw in loop bolt, so I rang our local 4WD shop where we bought them to ask about the strength of the point. He informed me that no vehicle has actual recovery points and that they are only for towing (Toyotas included).
Given that everyone uses those points from what was said in the course (and we did use them for a rescue in the course) can you let me know that they are OK?
There’s a serious bit of a… saving going on by manufacturers and their dealer network using the quaint term “towing” for vehicle retrieval. I suppose they can never bank on the intelligence of some people doing clearly dangerous things, so better to downplay the merits of the points. The Prado’s welded wire loops in the front have proven to be durable on the courses thus far. Make sure though it is the flatter forward facing loop that you use with a rated shackle and not the downward facing version. The downward one is for shipping. I’m happy to recommend them for snatch-strap retrievals with the rider that any component might fail if the load imposed is too great, the item is damaged or the technique and connection is flawed. The reason we use 2 straps with a dampener is to try and soften the loads and forces and so far it seems to work even on Prados and Hiluxes as they seem to share the same front points.
The screw in eye is something I see on a lot of on AWDs now. The bolts look to be high tensile and fine threaded which is good, but I suspect with enough of a jag the threads might let go. Might see if I can find out what sort of shearing force would have to be applied. What we do with AWDs in the same predicament is try a couple of gentle tugs to break the initial “suction” of ground Vs vehicle. Once loose the vehicle will usually drive out with the lightest of assistance.
The best retrieval point of all is at the back, the Hayman Reese styled towbar set-up with the drawbar removed. So if you can pull from the rear I think you’ll have greater guarantees of success. One thing to watch out for though with the AWDs and especially those that are monocoque construction, is to regularly inspect the “chassis” folds in the floor of the vehicle where the towbar attaches to see if there’s any distortion or tearing?
Hope that helps.
I have a new 2012 Toyota Hilux with 265/65 R17 tyres and I want to fit decent offroad tyres. I was hoping to go with Cooper ST Maxx on a 16 inch rim which give similar diameter, but I’m not sure if there are 16 inch rims (steel or alloy) that fit the Hilux?
If not, would going to a 265/70 R17 in the Cooper ST Maxx defect the vehicle?
Thanks for your enquiry, selecting an appropriate tyre/wheel combination is an important aspect of 4WD operation so you need to get it right.
The first question I’d be asking you is what type of 4WDing will you be doing and how often? If you’re a South Australian resident then sand and a small bit of mud and rock will likely be the norm, whereas in Victoria a tyre with more of a mud focus might be important. The other reality is that for the most part our driving will be on bitumen.
I’m not a big fan of patterns that are too extreme and mud focussed. On bitumen roads that are wet M/T patterns are dangerous on corners with poor adhesion. Not only is that a problem but so too the noise they generate and on a long distance road trip they’ll be tedious and add an extra dimension of fatigue for the driver to cope with.
I agree with you on your desire to go for a 16″ rim. There’s plenty of tyre options with 16″ rims, 17″ not quite so. What you will have to watch though is the rolling diameter of the tyre. Diameters legally are only allowed to vary (increase) by around 25mm here in SA, but it might be otherwise in other States. A word of caution here is that those drivers who’ve elected to go way in excess of that size permitted are asking for trouble. What they fail to understand is that increasing the height of the tyre and therefore the height of the vehicle increases the rollover potential, but also decreases the braking performance, as the larger diameter and mass adds extra momentum to the wheel, making it harder for the brakes to slow the vehicle. Additionally the gearing of the vehicle will be affected making it taller, so steep downhill descents in LOW range won’t be as good and day-to-day driving will be sluggish in accelerating too. So a modest increase is welcome for better clearance (something Hilux definitely needs help with) but not at the expense of you or your passengers safety.
Now onto tyres. Personally I don’t like Cooper products at all.
Cooper, as are Mickey Thompson, some BF Goodrich and Goodyear products are either designed or manufactured in the USA. The American driving experience is mostly concrete highways with the occasional dirt road trip. Each of these manufacturers make their tyres with this in mind, using rubber compounds that are hard (to give excellent durability and wear rates on the concrete), but incredibly brittle on Aussie gravel roads. Tyre tread tearing/chipping is the norm with these brands.
We use Bridgestone products here and have done for 20 years. Their Light Truck (LT) range is very good and I don’t have any trouble recommending them.
Your current 17″ tyre/wheel combo has a rolling diameter of 776mm. You need to aim for a similar size in a 16″ fitment with the allowable increase. Luckily for you the D697 in an LT265/75R16 size will do it at around 803mm. This is a great tyre which we are currently running after prior success with the just superseded D694. The D697 has a new tread design that is grippy on the bitumen, excellent in sand and on rock and pretty good in mud, not as good as a dedicated M/T, but as a compromise tyre across all surfaces, brilliant. The other advantage with this size is the increase in tyre strength measured by the load index. The D697 offers 123 (1550kgs) and coupled to the R speed rating (170kph) it’ll cover both heavy loads and nearly match the original speed rating of the standard 17″ fitment, which most likely would have been S (180kph), but easily beat it in carrying capacity.
One thing that might need to change is the suspension on your vehicle. At standard height you might find these tyres at this size foul under the front guards at either full compression or extension on a turn. Talk to ARB about an Old Man Emu kit for your vehicle. it’ll make a world of difference.
A lot of my clients talk about Dynamic wheels as being OK, so I’ve copied the URL of their steel wheel ebrochure for you to browse and they list Hilux to 2009. Might need to check with them to see if there’s any issues with your later model.
We have traditionally used Mullins/CSA wheels on our vehicles as they are SA based but with national distribution. I’ve attached their steel wheel ebrochure for you to browse as they too list the Hilux (see above).
So to conclude, what you are proposing is do-able and likely legal using the above information.
Good luck with your future 4WDing.
Thanks for an awesome weekend and for letting me drive your car on Sunday. Could you please suggest some new tyres for my colorado. My horsefloat on its own weighs 1999kgs and the horse I usually tow in it weighs about 500kgs. The float does take two horses so the other two weigh about 500kgs and 250kgs.
I would suggest what we run on the Navara at the moment, the Bridgestone D697 Desert Dueler.
I had a look at the size chart and this would work with your current vehicle specification:
D697 – 245/70R16 113 S
Re pressure when you get them, consult with your tyre placard. If you’re confused take a picture of the placard and send it to me and I’ll explain it. We need to factor the horse weights as well.
Further to the info in the course I am costing the updating of our equipment for the vehicles.
Can you please answer the following:
What sort of tyre gauges do you use?
Given that we have two Toyota Prados and a Holden Captiva. (Although the Captiva will only be used on dirt roads and well-made farm tracks it may need to be pulled out if it gets bogged).
What length and weight bearing level do we need for the snatch straps? (RLL and MBS)
What weight bearing minimum and size do we need for the U bolts?
Currently I have in my bag a Hafner (metal/dial type) gauge bought from an AutoPro store (but I’ve seen them at Sprint Auto Parts too) and we’ve had them in the past too and work well. ARB sell a VDO gauge with some of their compressors and recently have made their own up which are robust too. Expect to pay around $25.
Use only ARB versions, suggest the ARB705 at 9m long with an 8000kg breaking strength.
We carry 2 sizes, a 3.25T and 4.7T so we’ve got all vehicle types covered.
Hope that helps!
I have the Bridgestones AT/LT D697 ,size is 265/65 R17.
What tyre pressure do you recommend for the front and rear for the road?
I’ve had a look at the book and the minimum pressure recommendation is 250kPa or 36psi for that size tyre. Now the Challenger won’t be carrying 1640kgs across one axle, so 36psi is likely to be a little high so maybe what you should do is start at 30psi front and rear and drive it for a week and see what it feels like, then increase the following week to 32psi, then 34psi, finally 36psi. I reckon at 36psi you’ll be getting some decent bumps on potholes, so the lower settings will be more comfortable around town.
Fully laden though it’ll be different where the 36psi in the rear will likely be right and a lower figure in the front, perhaps 32-34psi. If you tow anything like a camper or caravan then maybe the backs will need 300kPa or 43psi, but the only way to accurately work that out is via a weighbridge. Look at the chart and you’ll see the increase in weight per tyre demands and increase in pressure.
Hope that helps.
I’d just like to say how much I liked the 2 day training course on Thursday/ Friday… I had a lot of fun!
I was writing to see if you guys could put together an essential 4WD kit list that we could use in all of our 4WDs
Tyre gauge, Compressor, Shovel thing like that?
your help would be most appreciated.
Glad to hear the training went well and yes it was a good couple of days!
A basic kit should include the following:
1 x Long handled shovel – suggest fibreglass handle with screw together capability (reduces overall length for storage)
2 x ARB snatch straps – 9,000kgs loading/9 metres long
1 x newspaper roll covered in electrical tape (that’ll be cheap)
2 x Bow shackles – 1 x 3.25T and 1 x 4.7T
1 x poly tarp – suggest 2.7m x 2.7m or similar
1 x dial type tyre pressure gauge (metal construction)
1 x ARB air compressor (tackle box style with pump/air lead/alligator clips with lead to battery)
With this you should be able to do most things. It’s also portable enough to pack on a plane if you had to fly-in, fly-out to a location.
Suggest to purchase you contact a mate of mine Michael Davis who is the State Manager for ARB, phone 82445001, either he or one of his crew will be able to assist.
Hope that helps, look forward to seeing you again!
David how are you.
… pretty soon I am going to end up living off roading !
Just came back from a wonderful place in the mountains of Peru, did a lot of horseback ridding and trekking, but the interesting part was the ROAD to get there. It was only 100 km and took about 4 hours !
My trusted Prado did the job well, but I decided on the road to get a more robust vehicle now.
I know that Toyota Australia sells the LC 76 GXL Wagon (V8 Diesel)… that is what I want ! My problem is that Toyota does not sell it anywhere that I have looked for (Mexico, Brazil, Ecuador, Chile Argentina etc). And in Australia you drive on the left (right and wheel) so that is not good for us.
Do you happen to know where else I could get this truck from ? with a wheel on the left ?
Hope all is well there.
Glad to hear your intent is to live off 4WDing, and I’m envious of your trek to Peru (not so sure about the horses though). Wow 100kms in 4 hours that must have been lots of LOW range work! I’m off tomorrow into our nearest serious mountains the Flinders Ranges (although just a fraction of the ones you have over there at barely 1000m high) guiding a group of people with some new skills. There’ll be some pictures on the website next week so you’ll be able to see where we went.
Now the 76 wagon, that’s a tough question. We get them in here all the time with Government and mining industry users. I’ll ask someone I know at Toyota Australia and see if he can tell me the world markets for LHD models. Somewhere they must use them? They’re a pretty good unit but pretty small in the back for carrying cargo, there’s not a lot of space.
Have you considered a Land Rover Defender 110? I would have thought they’d be sold in South America? The fit and finish isn’t as good as it’s almost a handmade vehicle, but they’re a pretty solid machine and look cool with heaps of accessories made for them right around the world. I had one between 2002 and 2007 and did around 150,000kms in it. With a Japanese 4WD you can attend to the servicing pretty casually, but with a Defender you’ve got to be pretty involved with its upkeep. It’s a bit like a demanding mistress, keep her happy and you’ll get the ride of your life, but ignore her and you’ll pay dearly!
Send us some pics from Peru and a couple of paragraphs about the journey.
We have had several staff go through your training course. We normally use Landcrusiers with the standard “4×4” system and our rules are they must be in four wheel drive as soon as they hit the dirt. We now have Prados on site as well but this means how to use the centre diff lock has become a issue of great discussion. I was hoping you could help us with if we should be using the centre diff lock as soon as we hit the dirt or only when we are crossing difficult terrain. The road we take to site involves a 80kmph section that is in good condition but is rough in parts and then a 50kmph zone with some water over the roads in parts.
Any advice on when we should be using the centre diff lock would be greatly appreciated.
Thanks for your email and your concern over the use of the centre diff-lock is worth raising to ensure the safety of your fellow drivers and the longevity of the vehicles.
Firstly we have to be careful in making the recommendation I’m about to make because there has been a system employed by Toyota that has largely remained the same since the inception of the Prado here in Australia (the 90 series in 1996), being a Full-Time 4WD driveline. But with the recent release of the current 150 series, there’s been some subtle changes and in light of me recently driving the 200 series Land Cruiser, the Prado’s bigger brother, there’s a chance its electronics may (or will) have already snuck over to the 150 Prado.
So for Prados built between 1996 and 2009 (90 and 120 series) the recommendation is that use on any dirt road surface should be accompanied with centre diff-lock (CDL) engaged. This locks up the transfer case to provide the same sort of mobility (50/50% split of torque across front an rear axles) as you’d expect with your 70 series Land Cruiser trayback utes which are Part-Time 4WDs. In their normal “open” Full-Time mode there’s a 30/70% bias to the rear which can lead to oversteer on dirt.
The 120 series Prados from 2002-2009 had a Torsen (Torque-Sensing) centre-differential which is a bit like a limited slip differential (seen in rear axles) or LSD, able to recognise an imbalance in the torque delivery (say in the case of excessive wheelspin) and clamp up to direct the torque across the driveline to where it could be better used. That’s useful but from our experience the reaction delay will be long enough to get the vehicle out of shape in an emergency. Better to lock the CDL in advance.
Something else seen on the 120 series in the upper class models was the introduction of electronic traction control (ETC) and vehicle stability control (VSC) mated to the anti-lock braking system (ABS), so all VX and Grande models got this as standard, dumbed-down GX and GXL didn’t. Both ETC and VSC add significant other safety enhancements in vehicle handling and should form the basis of any new vehicle purchases for your fleet in concert with ABS. By the way don’t buy any secondhand 120 Grandes, they come with air suspension in the rear and are difficult to live with in a 4WD environment, they’re really only a “townie” 4WD.
ETC is useful in off-road situations because it brakes spinning wheels on loose surfaces and directs the torque to the wheels that have grip, great for banging over rocks or in mud to maintain momentum. ETC will also work on-road, say in a situation where gravel or ice might be on a bitumen road and likely to induce unwanted wheelspin. Again as the wheelspin occurs, the brakes are applied in rapid pulses to that spinning wheel to correct the imbalance. VSC works at higher speeds countering over or understeer by decelerating the engine and applying the brakes to one or more wheels and thus preventing the potential for a serious accident. This will all be going on irrespective of what you are doing as a driver, because the technology is smarter and faster than a human in reaction times.
From my experience with the new 150 series, use of the CDL still permits the ETC/VSC programs to operate in the background in HIGH range and this is desirable. Having the transmission locked up 50/50 affords the most neutral handling/control and offers greater safety than the 30/70 around town mode with the CDL open. We’re trying to prevent a situation from occurring before it happens in using it this way.
My worry as I stated in the earlier paragraph is that the 200 series Land Cruiser disappointingly disables the ETC/VSC programs when the CDL is engaged in HIGH range leaving the driver to rely on the advantage of 50/50 torque delivery coupled up to their personal vehicle handling skills in a slide or loss of control. Some of us are good at that but most aren’t.
If you are running 150 series Prados I want you to let me know what happens when you engage the CDL in HIGH range? Does an amber warning light come up on the dash saying VSC is off? If so then we have to run contrary advice and recommend CDL is left alone on the dirt roads you are driving on, that way the ETC/VSC package will still operate.
I’m sorry there’s been a bit to digest here but without knowing which model we were talking about I had to canvass all possibilities. Full-Time 4WDs are really good on wet bitumen roads, much better than a 2WD. On dirt historically they were better with CDL engaged, but with the advances in ABS technologies and how its applied we need to look closely at what each manufacturer is doing before making any sweeping statements.
Please note this:
- In a Part-Time 4WD use HIGH range 4WD on all dirt surfaces
- In a Part-Time 4WD NEVER use HIGH or LOW range 4WD on bitumen/concrete/paving, you’ll damage the transmission
- In a Full-Time 4WD use of the CDL is recommended (with caveats above considered) on dirt surfaces
- In a Full-Time 4WD NEVER use the CDL in HIGH or LOW range 4WD on bitumen/concrete/paving, you’ll damage the transmission
- Always wear a seatbelt
- Always run with headlights on
- Never drive faster than 80kph on dirt
Could you please help me please?
The information you told me about tyres last week when I picked up the Satphone for Andrew’s field trip to the Outback was very interesting and I would like to have him understand it. Could you send me your recommendations so I can forward that to him?
He’s hired a Toyota Prado for the trip.
By chance we have in here today on a course a Prado with hopefully the appropriate tyre placard.
It will help to illustrate what the manufacturer recommends for inflation and should be used as a starting point. The danger for people out in the field without the benefit of a lot of experience is serious tyre damage that can leave them stranded or worse create the potential for running off the road and maybe even rolling the vehicle. Whilst manufacturers insist on putting unsuitable tyres on their vehicles this danger will persist. If you had your own dedicated vehicle I’d recommend selecting an “LT” or Light Truck type of tyre as they are significantly stronger, but I’ll leave the explanation on that to another time.
Depending on which Prado Andrew has hired (there’s 2 likely models either the GX or GXL based on the shape that’s been out for around 9 months now) the tyre placard will state the following:
2010 GX Prado – 245/70R17 – Front 200kPa + Rear 200kPa (unladen) or Front 200kPa + Rear 220kPa (laden)
2010 GXL Prado – 265/65R17 – Front 200kPa + Rear 200kPa (for both unladen & laden situations)
Here’s a pressure conversion to PSI
200kPa = 29PSI
220kPa = 32PSI
Now our formula for tyre protection whilst operating on less than perfect surfaces follows:
When you go onto well-made dirt tracks try a 20% reduction in pressure and accompanied by 20% reduction in speed, now no faster than 80kph (and don’t forget to use HIGH range 4WD). You may find that when you get to significantly corrugated dirt roads that have sharper rocks a further reduction is warranted, say another 20% and no faster than 60kph.
Of course on your genuine 4WD tracks whether they be sandy or muddy, getting down to between 15-20PSI is highly recommended, but again reduce your speed to between 25-50kph and at the lower end of the pressure scale make sure your turns are wide and gentle. Excessive speed may cause the tyre to pop off its rim.
Additionally there’s too much hoo-ha written about pressure creep due to the ambient temperature and speed/friction. To keep it simple set your primary pressures at the start of the day when the tyre is cold. Make all your adjustments at the time you need to make them and at what the gauge is showing you at that time. When you’ve done with the off-road elements and it’s time to return to higher speeds on bitumen, pump them up again to the above on-road recommendations. Next morning check/adjust/reset again once cold.
Hope that helps, don’t hesitate to call me if there’s additional advice you require.
One of our drivers had an incident recently on the highway in the wet where the vehicle he was driving aquaplaned and spun off the road, fortunately coming to a rest on the grassy verge without any other damage than that done to the colour of his underpants!
We’d done some reading on the internet (I’ll forward the link) and there seems to be some advice that suggests pushing the clutch in, in these circumstances, is the right way to go accompanied by slowing down.
What are your thoughts?
This isn’t the first time I’ve been asked this so I went back to some correspondence I wrote back in 2008 as it’s still relevant and amended it where I thought appropriate.
The general tone of the internet advice you provided is intended to be helpful and for the most part is useful in reminding drivers of their responsibilities when driving in less than perfect conditions, however the advice on aquaplaning is incorrect and not thought through well at all.
Here are some points to consider:
- Aquaplaning occurs when the road surface is flooded with water after a heavy downpour or after a culvert has overflowed and directed water onto the roadspace to the point where as a vehicle’s wheels pass through the flooded area the tyre actually sits up on top of the moisture and “floats” rather than penetrating the water, clearing the roadspace and retaining its ordinary contact grip with the road surface
- This occurs for a number of reasons and it’s nearly all to do with speed. Firstly a tyre is designed to act like a pump on a wet road. The network of tread blocks and their channels direct the water to the outside edge of the tyre to disperse the moisture away from the tyre’s face. The sipes (the small “cuts”) on the tread blocks squeegee the bitumen to give the face of the tyre something to grip to. If you seek out the speed rating of the tyre you will see that different tyre types as fitted to different vehicles, have differing speed ratings to suit the likely maximum speed of the vehicle. Typically Australian vehicles have speed ratings between N (140kph) and H (210kph), which are well in excess of the maximum highway speed posted in this country. Makers when arriving at these maximum speed capabilities factor in the effect of wet-weather on their tyre’s grip ability and design the tread patterns to accommodate a certain amount of moisture at that maximum speed, the faster they go the faster they must pump the road dry. If the road surface is too flooded, or the tyre is worn, or the vehicle is being driven too quickly, or turning too sharply, the wet-weather grip formula will be overtaken and a loss of control/grip will result.
- Tyres with less than 50% tread will be affected in the wet. Tyres worn down to the TWI (Tread Wear Indicator) may as well be bald in downpours, bald tyres are a disaster waiting to happen wet or dry! Tyres that are over or under-inflated will be affected too, check that your tyres at least match the recommended pressures seen on your tyre placard.
- From my experience and the experience of colleagues both here and overseas, these aquaplaning moments are usually brief and can catch a driver by surprise. Sometimes you can see a roadspace that is flooded and can anticipate the situation before you get there and make the necessary speed adjustment, but more often than not the moment happens in an instant, lasts a few seconds and settles almost as quickly. In a worst-case situation the effect on the vehicle can be dramatic and potentially life-threatening if the driver reacts poorly.
- The advice you’ve provided is a sore point here. What a driver is looking to do is regain control of the vehicle. The first response is to get off the accelerator. This will achieve two things, deny wheelspin and regain some traction.
- The second response might be to apply some corrective steering (if the vehicle has deviated from the chosen path) and possibly apply some subtle braking. In non-ABS vehicles that will require some disciplined “threshold” braking to manage the pedal pressure avoiding a lock-up (consistent pedal pressure – no pumping of the pedal please), whereas in an ABS vehicle the driver can confidently apply any amount of pressure to the pedal to achieve the retardation required and the electronics will work out what to do without a skid/loss of grip.
- If the vehicle had the new technology of VSC (Vehicle Stability Control) there’d be a pretty good chance the vehicle would have been able to mostly sort it out itself. By selective braking one or more wheels and automatically decelerating the engine the vehicle can correct some oversteer and understeer situations despite what the driver is doing.
- In all cases the transmission should be left in gear and always engaged, manual or automatic!
- The correspondent recommends depressing the clutch on a manual and on an automatic applying the brake. This is inconsistent and will create confusion amongst drivers.
- In a manual if the clutch is depressed the transmission will be disengaged and the vehicle will “free-wheel” (this traditionally has been called “Angels” gear as it usually means a loss of control and a quick trip to heaven) and initially the vehicle will appear to accelerate as load is taken from the transmission and no resistance courtesy of engine braking is applied. It is always better to leave the clutch alone, lift off the accelerator and let the engine slow the vehicle ensuring it will track truly rather than free-wheel and possibly start to rotate and spin, requiring more of the driver to correct. If need be corrective braking (see 6) may be applied. Engine-braking and ordinary braking together will always slow a vehicle faster and more predictably than pushing in the clutch in concert with the brake pedal. Leave the clutch alone!!!
- In an automatic lifting off the accelerator might be all that’s required, supplemented with some braking and corrective steering as well if need be.
- Emergency situations always require drivers to take a cool, calm and measured response that is uncluttered with panic or unnecessary or less important considerations about preserving the vehicle and its parts. The driver and other human occupants are the important things. The first focus is to restore grip and control and to do it without taking your eyes off the road so you can concentrate on finding an escape route, accompanied by the measured responses in steering and braking. Get that right and you’ll live to tell the tale.
- Nearly all of us in our pre-licence days were told by our teachers that when you had to brake you apply the clutch at the same time so as to save the engine from stalling. I’d agree with that around town when normally pulling up at a set of lights in the right fashion. I’d additionally supplement that deceleration with down-changes in the gears, coming off the clutch each time and using engine braking as well, pushing the clutch in just prior to rolling to a stop. Many people are quick to push the clutch in, in an emergency, but this is counter-productive and will only extend braking distances. You won’t have time in any emergency to fumble around changing gears so it’s best to stay with what you’ve got gear-wise and concentrate on pointing the vehicle the right direction with all of the previous recommendations in tow.
Hope that helps!
Thanks for the intro course last Saturday, Sally and I found it very useful.
We have a couple of 4WD questions for you. (Our car is a Suzuki Vitara 2008 Diesel Manual)
- You mentioned that you could get upgraded coils and shock absorbers for the Vitara – who does those and what are the benefits?
- I have not been able to find a “light truck tyre” for the Vitara – the size is 225/65/R17 – the best on offer for our car seems to be the Bridgestone Dueller 694 A/T – what do you think? Drew mentioned that you may be able change the size slightly without adverse effects.
Alistair and Sally McHenry
I mentioned on Saturday that there were some gains to be had by improving the suspension of the Vitara and seeing if there was a replacement tyre that too could offer some benefits.
The problem with standard shocks and springs is they are set for light to median loads and in the case of AWDs and light duty 4WDs such as yours, bitumen road comfort is the key parameter they tune their targets on. That satisfies 90% of owners as there’s only around 10% of us who go bush. In your case with great aspirations to explore what this great country has to offer the standard set-up is too light and may fail in difficult conditions. In the first instance with your suspension the benefits with the right system will be a subtle increase in ride height which improves ground clearance, more wheel travel to soak up the lumps and bumps better, a less “floaty” feel with the suspension at higher speeds, surer steering, better load carrying. I have put through a call to Michael Davis local manager of ARB to ask whether there is an Old Man Emu suspension kit for your vehicle and will advise when I know. In the meantime I’ve noted that Pedders Suspension offer in their Trak Ryder range a kit that might work. My first preference would be the ARB OME system.
On the tyres I hadn’t realised how problematic that would be. Since the introduction of 17″ and 18″ wheels tyre choices for off-road usage have become tricky. The safety advantages of bigger brake diameters is what has driven bigger wheels, but tyre makers are loathed to invest heavily in narrow focus tyre types, hence reducing our options. You’re right in looking at Bridgestone’s range, we’ve used it since we started and have great faith in their product. I think you’ve already selected the standard size D694 225/65 R 17 with the 102 load index for the pair of replacement tyres you needed recently. I think a better choice that’s still legal would be the D694 225/70R17 with the 108 load index.
Load index is the key to tyre strength and the difference between the 102 and the 108 is a healthy 15% increase, 850kgs compared to 1000kgs carrying capacity. You’ll also pick up some extra ground clearance under the vehicle (12mm), which is handy. Unfortunately these tyres are not Light Truck offerings, but reinforced Passenger tyres, so to avoid the puncture potential you’ll need to be really vigilant with your pressure regime (per our advice on Wednesday night). I searched a number of other tyre makers offerings to see if there was a Light Truck alternative but alas they were all too big and likely to foul on your bodywork and be illegal and cause speedo inaccuracies.
I think you’d mentioned to Drew that you wanted a bullbar on the car too, which is good for remote area work and ARB certainly make the best products out of steel in that regard. If you do get one the suspension will be necessary to carry the extra weight, particularly over the front axle.
So to rework the tyres on the vehicle contact Laurie or Anthony at the Bridgestone BSelect store at North East Road at Windsor Gardens, phone 83691045. They too will be able to source the suspension if ARB can’t assist.
Answer follow up
Got the response back from Michael and yes there’s a spring kit for it, details below:
- Front OME623 (offers 20mm lift)
- Rear OME625 (offers 20mm lift)
ARB is at Regency Park, phone 82445001, if Michael’s busy one of the sales team should be able to oblige. Make sure you let them know you’re a VIP customer of ours. The lift in height is modest which is good, as you don’t want to create a top-heavy vehicle, but what it will do is transform the vehicle into a far safer handling and steering machine. I’ve done this to every single one of my 4WDs over the last twenty years and it makes a positive difference.
Hi David, I enjoyed and learned a lot from the first time out course i did in March this year and was wondering what the next step is in learning more about 4wding.
Since the course I’ve only done beach driving on KI and am going to Yorke Peninsula next month. Do you know of anywhere on YP that I can go off-road and or on to beaches?
Sorry David I forgot to ask you about tyres. You made a big deal about tyres in the course and I’m confused about what to do. I have a prado kakadu and will take it off road up to 10 times a year, Most off roading will be beaches and dirt roads but i do also want to go north and explore cooper creek region. The tyres on it now are 265/65R18 H110. My car is mainly used around town so I’m wondering how much ride quality and extra noise i get when i get a LT tyre. What are your thoughts?
Unfortunately you have a very difficult wheel size to manage. As the braking evolution of 4WDs has revolved around bigger brake rotor diameters requiring bigger wheels, increasing in line with passenger car design, vehicles have been stopping in shorter distances, which is good, but not without some drawbacks. Its also been trendy to fit bigger wheels and low profile tyres to vehicles from an aesthetic standpoint, but hardly a practical one. I have numerous Land Rover Discovery 3 & 4 clients running 18″ wheels with the same dilemma as you, wanting better security from punctures when they go bush. Eighteen-inchers aren’t going to do that.
I’ve searched high and low for uprated tyres in this size and I can tell you there’s nothing. Any other tyre makers building that size will only be offering exactly the same Load Index and likely Speed Rating as that that came with your vehicle, which confirms that they are merely high speed passenger tyres and wholly unsuited to gravel roads. No better than what you’ve currently got.
If you wanted to make a change that works, pick up a set of steel 17″ wheels and fit a set of LT265/70R17 rubber or LT275/65R17. The rolling diameter is identical or very close to that you currently have but the big difference is Light Truck construction, thicker tread depth (13mm compared to only 9mm) and a much higher Load Index which is the only true barometer for puncture resistance and longevity. In that size there’s two really good products, the Bridgestone D694LT in the LT275/65R17 with a 118 load (1320kgs) or the Toyo OPAT in a LT265/70R17 with a remarkable 121 load (1450kgs). In each case that’s either a 25% increase for the Bridgestone or 37% increase with the OPAT. The D694 measures 790mm, the OPAT 802mm, your existing 18″ combo rolls out at 802mm.
I’d suggest calling Laurie or Anthony at the BSelect (Bridgestone) store at Windsor Gardens phone 83691045 for advice. They’ll be able to ascertain the wheel offset and PCD measure for the wheels, cost it and install with a wheel align. Laurie is one of my part-time trainers and a great bloke.
On the subject of ride quality you won’t be making any sacrifices at all as from my experience standard tyres are usually crap. With these new products gone will be the vague steering, the floaty almost disconnected feel from the road, with much better stopping distances and the previously mentioned benefits in puncture prevention and longevity (expect 80,000kms instead of maybe 35,000kms).
Re locations to visit, YP doesn’t have a lot to offer as much of the Peninsula is owned freehold. There’s a couple of sandy tracks out the back of Port Victoria and that’s about it. Eyre Peninsula is a whole lot different, give that a visit some time.
Here’s the email as requested about my 80s series tyres being illegal due to the incorrect size fitted by my dealer and please could you suggest something more appropriate for my cruiser and I will follow that up with the tyre supplier. It’s a 1992 model HZJ80 – tyre size is 265/75R16 116T.
Thanks for the best day ever on Saturday, it was truly exhilarating, exciting and exhausting and I loved it!
Here’s the info for you.
- The SA Road Traffic Act states that “no part of the tyres and wheels of a vehicle may protrude beyond the vehicle’s bodywork”. The width of your new tyres currently does do that.
- The tyres fitted by your retailer are 265/70R16 which are OK for the GXL and Sahara 80 series Land Cruisers of the day (that was their standard size mid way through the vehicle’s model life) because they have wheelarch extensions to cover the tyre, but not for the commercial model that you’ve got which does not.
- The placard on the vehicle lists the traditional tall skinny, a 7.50R16. I’m not a big fan of that tyre size as it only offers up a very limited product and pattern range, typically the original Dunlop Road Grippers and they were junk.
- The nearest equivalent to the 7.50 is the more common these days LT235/85R16, which is what we’ve used for years on a number of our vehicles with great success and the same size we recommend to our clients in SA Government on their LandCruiser 100 and 70 series vehicles. It’s also used by BHP at Olympic Dam courtesy of our recommendations on all of their full-size Toyota fleet. This tyre size also will fit on your existing rims as the design rim width codes allow 5.5″ – 7″ wheel widths when fitting up a 235.
- The only potential wheel problem you still might have is with the offset. The centre of the wheel is welded to the rim at a particular position per vehicle to accommodate the individual brakes/hub size and to allow the wheel to fit under the guard comfortably without any body contact. I’m hopeful the original owner did his/her homework with the wheel selection and that once the new tyre size is fitted, the narrower profile of the tyre will then sit inside the guard, as is required by law. If they don’t you better let me know before you go buying new rims.
- My favourite 235 is the Bridgestone 661 Desert Dueler. This tyre has an extraordinary reputation in commercial circles, as it has an impressive 120 load index = 1400kgs carrying capacity.
- The higher the load index the better for a 4WD going bush, because load index is a good indicator of puncture resistance/tyre strength. By way of a comparison the 265s you currently have have only a 112 load index = 1120kgs and an “S” speed rating (180kph) which immediately tells me they’re a Passenger car tyre, not Light Truck (the devil’s in the detail) and are no good for rough bush tracks, better suited to the bitumen.
Cleverly I haven’t got the pics with me today I took on Saturday that show just how much your tyres stick out from the guards and I also took a pic of the placard that clearly states 7.50R16 as the standard size. These are good for a reference so I’ll send them across via email to you, but the info above should be enough ammunition. Tyre brands to avoid in my humble opinion include Cooper, Mickey Thompson, Hankook, Kumho. Let me know if they’re confusing you?
Hi David – I had a quick look on the Goodyear website – these are the tyres with a 120 load rating – speed rating Q (160) and R (170), Wrangler MTR Kevlar, Wrangler Duratrac, Wrangler Silent Armor, GrandTrek AT3
Thanks for doing the detective work, I reckon the Silent Armour is the go, the MTR is way-too aggressive and will be noisy, the Duratrac marginally quieter, Grand Treks are junk.
See how you go?
Went there this morning to meet with the rep, ended up FOUR blokes looking at my tyres and me just looking at them shaking my head. I stood my ground on the fact they were illegal and I should have been advised, plus they were unsuitable for what I had in mind driving wise, and all of them said to me that they still don’t think that they’re defectable, and that the tyres would have held up in most 4×4 situations… geez how stubborn are some people! Long story short they changed them over today to the Silent Armours and 235 85 R16 and what do you know, almost perfect fit! Thanks for your help you were right all along and I didn’t deviate from what you said and they did what I wanted, good lesson for me. And all at no charge, bet they were glad to see me leave.
Firstly thanks to you and Alex for the weekend, Mike any myself got a lot out of it, on top a that we really enjoyed it and look forward to seeing the photos. Our next task is to try and talk the partners into it but they are cautious, concerned it will be beyond them but I am hoping the photos will help.
Following on from my question on Saturday, I want to replace the existing tyres on my new Challenger with some light truck tyres. Any suggestions or recommendations would be appreciated:
The compliance plate details are:
265/65 R 17 112 S
Front pressure = 200 kpa / 29 psi
Rear pressure (5 passengers) = 220 kpa / 32 psi
Rear pressure (Loaded) = 250 kpa / 36 psi
The tyres are 5x Bridgestone Dueler H/T 684 II, made in Thailand
If you don’t have any suggestions is there is anyone you recommend I should talk to.
Thanks for your mail and I am very pleased you gained some benefit from the training. It was a good day!
On the subject of your tyres here’s some advice that’ll work. On Pajeros and Prados we’ve had great success with either the:
1.Bridgestone 694 Desert Dueler in a 275/65R17 LT (275mm wide, 65% aspect ratio (height of sidewall), Radial, 17″ wheel diameter, Light Truck construction), 118 (Load Index of 1320kg), S (Speed Rating 180kph) 790mm diameter or a
2.Toyo OPAT 265/70R17 LT (265mm wide, 70% aspect ratio (height of sidewall), Radial, 17″ wheel diameter, Light Truck construction), 121 (Load Index of 1450kg), S (Speed Rating 180kph) 802mm diameter
Challenger is near identical to Pajero so I’ve no doubt that these tyres will work for you too. Both of these offer a significant improvement in puncture resistance courtesy of the enhanced load index and deeper tread depth. The boys at Bridgestone at Windsor Gardens here in Adelaide could sort this out for you pretty speedily, contact Anthony or Laurie on 08 83691045.
PS Have a look at what I thought of the D694LT at www.bridgestone.com.au
Firstly, thank you and Drew for a great First Time Out training course in March. Pauline & I both thought it was fantastic & we gained heaps from it. I have taken your advice & put Toyo Opat tyres on the Prado. Secondly, could you tell me what tyre pressure you would suggest for travelling on the Tanami Track & the Gibb River Rd. We leave in just over 2wks. time & it can’t come quick enough!!
We have kept in contact with Pat & Ian from the course & may meet up with them somewhere in June or so. They left on Tuesday this week heading west& then north up the coast.
Thanks again Dave & I look forward to hearing from you.
George & Pauline
Thanks for your kind words we appreciate your patronage and look forward to hearing instalments from the journey.
On the tyre pressure you’ll remember we asked everyone to locate their tyre placard on their vehicle and use those pressure settings as a starting point when fitted with OEM (original equipment manufacturer) tyres. This will be good for the bitumen. Once on the dirt we recommended a pressure reduction of 20%, accompanied by a speed reduction of 20% (now no faster than 80kph). I haven’t got a Prado placard in front of me but I think it said 29psi front, 34psi rear (if you could please verify that for me), but remember that was for those standard passenger tyres.
With your OPATs in a LT265/65R17 with 121S, I’ve consulted the TRA manual and at my best guess for a fully laden Prado at approximately 3,000kgs, with 1200kgs over the front axle and 1800kgs over the rear, it suggests 36psi front and 42psi rear for the bitumen. That sounds right to me based on past experience, so use the 20% formula on those, namely 29psi front and 33psi rear @ 80kph or less. Now where corrugations are particularly unpleasant (and I reckon Gibb River will be up there), a further reduction is warranted, because if we can get some flex into those sidewalls it’ll soak up the initial impact, leaving the suspension with less work to do. Try another 10%, namely 26psi front and 30psi rear @ 70kph or less. Remember that this is for a fully laden Prado, if you carry less than GVM you may not need these starting pressures. The only way you’ll find out is to get the car set-up as it would be for the journey and run it over a weighbridge three times. First the whole vehicle for GVM, then the front axle only, then the rear axle only. Armed with that we can consult the charts.
Glad to hear we’ve been instrumental in getting people together, it’s a great way to travel and share experiences!
Happy to help,
Dear Adventure 4WD,
We took your FTO 4WD course in January which we enjoyed very much.
We are looking for a little advice and clarification on tyre pressures as we have had much conflicting information from different sources.
We have taken your advice and upgraded our tires on our 2002 Nissan Patrol GU to BF Goodrich Mud-Terrain T/A KM2 (LT256/75R16 123/120Q M+S). We are currently in Broome and about to drive down the Tanami Track to Alice Springs.
When taking your course (when we had our Cooper A/T tyres, load index – 112), your instructors advised us to run our tyre pressures at 36psi font and back and increase to 42psi at the back when fully loaded.
The people at Bob Jane T-Mart in Karratha who sold us our new tyres felt 40psi all around was best.
The recommended cold tyre pressure stated on the label in our car is 29psi at the front and 36psi at the back.
Could you please recommend cold tire pressures for bitumen (we are currently running 40psi at the front and 42psi at the rear as we are carrying a large load at the back – full boot+roof top tent), and confirm that we should be dropping 20% pressure and speed on dirt tracks and running between 20psi-15psi on sand/beach.
Also, after viewing the BF Goodridge website, they state you need to adjust for a 4psi increase in pressure between cold and hot tires. Does this mean that if, for example, we wanted to run 40psi in a tyre, we should be setting a cold tyre pressure of 36psi?
Thanks for your help,
Ben and Bethan.
Thanks for your email and glad to hear you’re on the trail and it sounds like having a good time!
Firstly an apology. I think you had Drew and Laurie in attendance for your training sessions with us? Since I’ve received your mail I spoke to both of them and asked if they could recall the conversation and it appears that Laurie had noted that the sidewall on your Cooper stated “A/T” which is all-terrain, a throwaway bit of sidewall branding that really means very little these days as the real truth is whether it’s a light-truck (LT) specification and additionally what the load index is. He didn’t cast a glance to the index and construction and assumed it had the right LT value. Not so it would appear!
As your Cooper only had a load index of 112, it is essentially only a passenger car tyre and no better than the factory fitted tyres on originally.
With that in mind the Nissan’s tyre placard is correct, 29psi front and maximum of 36psi rear.
Now that you have true light truck tyres on with a very healthy 123 load index (that’s 1550kgs compared to only 1120kgs before, a 40% increase in capacity and therefore strength), we need to reassess the pressures.
The only accurate starting point for this is the Tyre and Rim Association Manual and it states the following for your previous rubber, P265/70R16 112S: Max inflation 250kPa or 36psi which is consistent with the Nissan placard. As I’m waiting for my new 2010 version of the TRA bible I can’t give you the light truck equivalent from the charts, but the size you are running is identical to that I’m using on our Navara with great success in a Bridgestone 694LT.
Assuming the car is fully loaded and at maximum GVM which is around 3050kgs for Patrols with a likely 35/65% split front to rear, 36psi is plenty for the front and 50psi for the rear. Remember this is assuming there’s around 1050kgs on the front axle and 2000kgs on the back and whilst driving on the bitumen. This might sound excessive for the rear but is accurate for bigger loads on full-sized wagons as from my experience they’re nearly always overloaded.
When you go onto well-made dirt tracks try a 20% reduction in pressure and accompanied by 20% reduction in speed, 29psi front and 40psi rear, now no faster than 80kph (and don’t forget to use HIGH range 4WD). You may find that when you get to significantly corrugated dirt roads that have sharp rocks a further reduction is warranted, say another 20% to 23psi front and 32psi rear and no faster than 60kph.
Of course on your genuine 4WD tracks whether they be sandy or muddy, getting down to between 15-20psi is highly recommended, but again reduce your speed to between 25-50kph and at the lower end of the pressure scale make sure your turns are wide and gentle. Excessive speed may cause the tyre to pop off its rim.
There’s too much hoo-ha written about pressure creep due to the ambient temperature and speed/friction. To keep it simple set your primary pressures at the start of the day when the tyre is cold. Make all your adjustments at the time you need to make them and at what the gauge is showing you at that time. When you’ve done with the off-road elements and it’s time to return to higher speeds on bitumen, pump them up again to the above on-road recommendations. Next morning check/adjust/reset again once cold.
Hope that helps, send us a pic of you and the car somewhere exotic and an explanation note of where it is and what you got up to???
PS I’m not a big fan of mud-terrain tyres in any other environment other than mud… Be very careful on bitumen roads at high speed that are wet and make sure you rotate them every 5,000kms, those big tread blocks go out of round very quickly!
You’ve delivered training for all our staff in the past and I have a query that’s come about after a couple of conversations we’ve had in the office since and that is the recommendation of 4WD usage at all times. Your trainers have explained that the vehicle is most stable in this mode, better for cornering and braking etc.
My manager is concerned though that this advice runs contrary to standard wisdom and that is not to use 4WD on bitumen. Whilst we do drive on dirt and on farmer’s properties from time to time, most of the running is on made roads to and from work sites.
The other issue we have is running costs with our fleet. We previously understood that the most economical mode is 2WD, wouldn’t it be better to leave the Pajeros in 2WD until 4WD is required and therefore save on fuel costs?
Lastly we run into trouble on occasions with tyres for our vehicles. You’d mentioned the differences between standard and truck tyres. Would the fitting of truck tyres to our vehicle make much difference in punctures and what are they like in terms of comfort.
Firstly to the 2WD Vs 4WD argument.
The Pajero is both a PART TIME and FULL TIME 4WD wagon and I reckon probably one of the best in our local marketplace as it is VERY safe.
- The only mid-full size wagon to be built on a monocoque platform with proper crash deformation zones
- Has a full complement of electronic safety features even in its basic model right through to the top of range see list below
- Those features include ABS brakes – anti-lock braking systems prevent wheel lock up under heavy braking and ensures steering control
- ETC – electronic traction control ensures that when grip is compromised or lost both on and off-road, traction can be regained swiftly without driver intervention
- VSC – vehicle stability control enables a driver to regain control of an oversteering or understeering vehicle at higher speeds via the vehicle electing to brake one or more wheels and/or decelerate the engine irrespective of what the driver is doing – it is a very clever car!
- With respect to the debate about using 4WD or not let’s look at the Pajero’s driveline.
It offers a multitude of options for the driver to select and the brilliance of the Super Select transmission as Mitsubishi call it, is that as the roadspace becomes progressively more difficult the driver simply shifts up through the range to gain more and more grip and capability.
Here’s an overview:
- 2H is recommended for city driving on DRY and WELL-MADE bitumen roads at slower speeds 0>80kph – 100% of drive goes through back wheels only (no good on dirt)
- 4H is the FULL-TIME or CONSTANT 4WD mode recommended for all other bitumen situations especially when the road is wet, bumpy/patchy, and/or at speed over any distance (this makes the Pajero behave like a Subaru with its all-wheel-drive system AWD) and makes the car very safe on the highway or around town. The drive split is 70% to the rear, 30% to the front (OK too on those rare hard-packed dirt roads like you see in the SE). There will be no appreciable difference in fuel used nor will there be any transmission damage when used on the bitumen!
- 4HLc is the PART-TIME 4WD mode only to be used on loose surfaces – any dirt or gravel, sand, mud, rocks that you’d find on rural and outback roads. If you use this mode on bitumen you’ll WIND UP the transmission and potentially DAMAGE it. We always say NEVER to use it on high friction surfaces – bitumen, concrete or paving. The drive split is even, 50/50% front and rear and provides the surest stability on gravel roads at speed.
- ALL of the above modes can be engaged on the move back and forth dependent on the road surface (see detail) at speeds up to 100 kph – although we have stipulated drivers should not be driving at speeds in excess of 80 kph on the dirt!!!
- 4LLc is another PART-TIME mode; again it cannot be used on high friction surfaces, but is ideal in difficult terrain where momentum is hard to find (mud, slush, deep sand and steep gradients). Engagement should be done whilst stationary (automatic transmissions need to be left in neutral before changing the transfer lever into 4LLc). Drive split is again 50/50%, but ground/travelling speed is significantly reduced.
We make it clear to our attendees that safety in the field should take precedence over any meagre cost disadvantage, every time. As stated previously the Pajero diesel used in the 4H (Constant 4WD) mode is particularly fuel-efficient and will not cost the organisation a noticeable amount more than if you ran in 2H all the time on the bitumen. However the enhancement in vehicle control is considerable and well worth exploiting. Remember Mitsubishi are not alone here, Subaru, as well as all other AWD makers, Toyota Prado and Land Cruiser 100 & 200 series, Land Rover Defender, Discovery and Range Rover, Nissan Pathfinder and others enjoy the benefits of a constant 4WD system with significantly less risk to rollovers and without a great cost in fuel consumption. As 4WDs account for nearly 60% of rollovers at speeds over 100kph on rural roads it is important to have as much safety at your disposal as possible.
So in answer to your second-last question, no I don’t believe 2WD usage should be encouraged, as this vehicle offers a safety advantage that should be used. I think you’d find that there would be greater fuel savings across your vehicle fleet if drivers paid weekly attention to maintaining their tyre pressure at the placarded levels, as under-inflated tyres use considerably more fuel than just about any other operation with perhaps the exception of using a roof rack.
If punctures are a big problem there’s a couple of ways to mitigate the issue. The first attack is to get the drivers to reduce their pressures (20-40% depending on terrain) and speeds when driving over surfaces likely to impact on the tyres, I suspect in your case the sharp gravel roads and those times you venture onto properties that are strewn with rocks and timber debris (don’t forget to pump them up when the speeds return to bitumen road running – refer tyre placard for pressures). The “standard” Passenger tyres that makers fit to their vehicles in stock form are pretty ordinary for people who have a true commercial application for the vehicle.
The “truck” Light Truck tyre is a much better proposition in terms of durability and longevity and will likely save the agency a reasonable amount in running costs. In your case to opt for the Light Truck alternative you’ll either have to as an agency buy the tyres outright out of your own operating budget or put a business case to your fleet managers to have them consider your request, done so on a case-by-case basis. In comfort terms I doubt you’d notice the difference, but in steering terms it’ll be so much better you won’t believe it!
I hope that helps and please contact me if there’s anything else I can add.