tyre pressures - a definitive answer

Too many variables to give a definitive answer.. Its a one that you need to talk with others with similar vehicle/trailer etc combo

Heres a few vairables off top of my head.

- Road conditions would be the biggest, theres 100s of different conditions alone on this one (dry sharp rocks, muddy clay, mud with sharp rocks too),
- Model of Car, small medium or large.
- Overall Weight, weight transfer front/rear (eg more at front than rear or other way round),
- Tires (Size, model, ply etc etc klms old), suspension - hard/soft new/worn,
- Weather conditions...
- Towing a trailer
- Top heavy 300kg on the roof etc etc.

You really need to take it on the day, check conditions, recent reports, talk to others coming the other way, see how they went etc.

What car do you have, and what tires etc, if you give a bit more info would be easier.

Take care.

Hi Bill
I took my final word on this subject a few years ago from a business man in birdsville who made many trips a year to Adelaide and he always ran 28 psi in his cruiser. I have made a habit of doing the same and have not had a fracture or sidewall flat since. I am not saying you wont get problems but it seems to work.
I wouldnt take my advice from any tyre seller anywhere as they do have an interest in tyre replacements.

IMO- the biggest issue is speed - slow down, and pick your best track through the obvious stones ....that is a hell of a good start - next ?......reduce pressures for the gravel roads. As you say, this softens the impact of stones, BUT must be in tandem with reduced speed, so that the other risk factors are not unduly compromised - IE you run into a dished section and plunge the suspension hard...this stresses the whole tyre bag and if bad enough the rim will be looking for somewhere to bottom. In many posts, speed is the common issue reported in a lot of vehicle incidents...rollovers etc. You just don't have time or traction to take evasive action. Hell....even careful types get tyre damage at sensible speeds while looking for stones....those that tear along with fully inflated tyres must be asking for it.

Bill,
I can only go on experience and a ruel that I follow.
40/90
No more than 40psi and no more than 90kph
The amount of air in the tyres will be diffrent depending on the vehicle and the weight.
The rear tyres are more likley to get a puncher than the fronts and tyres that are half worn or more will also get more punchers.
The other thing is to avoid hitting the big rocks, and sticks.
My cruiser is running 32x11.5x15 mud terrian (BFG) and the max pressure that I run is 38psi.

Wayne

Running a set of decent off-road tyres, will prevent/limit the sidewall damage. We always lower the tyre pressure for (a) a smoother ride and (b) better traction.

If you are running a set of highway terrain tyres, you will definately have issues with sidewalls being staked, and will need to keep the tyre pressure up.

hows this for definitive 55psi on the gibb river road = 2 destroyed tyres and 1 flat and later another destroyed tyre on another dirt road thanks to the forum I am now (hopefully) wiser

Thanks folks for the replies. Six responses out of six to date suggesting I reduce pressures - I think I'm starting to wake up and smell the coffee. Are Goodyear A/T's any good?
Cheers, Bill.

Hi I have BF A/T on my GU coil cab and run 40psi on the blacktop and ALWAYS drop them by 5PSI as soon as I go onto the dirt ,lower as required in mud,sand etc ,in all the trips I have done including Rudall river NP and the powerlines out of Perth 5 times I have never had a flat ,so with that track record I will continue to drop them (presures that is LOL) when I go bush .

Hi William
Just returned from a cape york trip & after reading some posts
on the subject of tyre pressures decided to drop the front to 28psi
& rear to 35psi, I can say it really improved the ride comfort in the
corrigations &washouts This is my 4th trip in this vehicle to the tip
previously i ran 35psi & 45psi ,call it lucky ,i have never had a flat
tyre on any of these trips my vehicle is a toyota hilux extra cab,which
i am running cooper st ,previous trips,include ,BFgoodrich &dunlops
I carry about 800kilos in weight,eg,boat,motor,extra fuel,fridge,generator
tent & many camping comforts,this is my experiance hope it makes sense
to you
Friar

From personal, and others experience, lower the pressure and lower the speed. It's hard to give that definitive answer as has been pointed out there are so many variables, particularly road conditions, tyre type, load and suspension setup. I use 28 - 30 psi as a start point and go from there.

Larry

And there ya go, as I said, no such thing as a definitive answer to the question!

No 2 answers are the same.