Tyre pressure off-road

[OldGreyFart Advanced Member Find all posts View Profile Close OldGreyFart]

I run my tyres around town at 40psi - Goodyear Wrangler ATs - as recommended by my local fitter. I am running a Prado which with full tanks and fridge etc is close to 2.7 tonnes.

I have been in the habit a airing down to 30psi when going onto dirt roads and using HL in my 120 - and down to 25psi if terrain is difficult and using LL and even lower if REALLY steep and difficult.

I have seen some discussions which suggested that there is no need to air down on dirt roads at all.

Would be interested in others views.

[Pugaree Member Find all posts View Profile Close Pugaree]

Has this thread been prompted by the one on ezploroz? I read through that one and found it quite interesting.

I'll be interested in what other have to say on this, sitting on the fence for now.

[AJ120 Out of control poster! Find all posts View Profile Close AJ120]

Tyre pressures are always going to be relevant to the road or track surface.

We have some "dirt" roads around here that are hard as rock, smooth as glass and you can easily drive on them at full road pressures and its a smoother ride than on half the "bitumen" roads around here.

For the most part though, dirt roads are not like that, they tend to be a bit rough, sometimes corrugated, often stony and regularly changing. I adjust my pressures nowadays to how the road feels, the rougher it gets the lower the tyre pressures and the lower the speed until I get the best compromise between ride and speed.

Talk to anyone that does tyre repairs or vehicle recoveries in the outback and they all tell you the same thing, most issues are caused by running your tyre pressures too high and driving to fast.

I have a brother in law who lives in the bush and drives on dirt roads around the farms all the time, he never adjusts tyre pressures but the roads he is on are generally pretty good. He went along the Oodnadatta track last year and ran road pressures and I think from memory had 7 flat tyres, I have been up and down that same track a number of times and never had a flat running 20 something PSI!

Cheers Andrew

[BlakMoth Avid PP Poster! Find all posts View Profile Close BlakMoth]

I spent most of the weekend driving around in 2nd gear high range on 13-16psi. Very soft sand, even had to use Low and the rear locker to get moving a couple of times.

My tyres are Dick Cepek Mud Country, very stiff side wall so have to lower them a bit more to bag out. Bob Jane said to pump them to 29 psi (200kpa) on road as that's what the tyre placard says on the car. Not sure if that's correct though.



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[Rusty62 Advanced Member Find all posts View Profile Close Rusty62]

Agree with Andrew. Found with mine if too much air the rear tends to bump steer. Lowering the pressure to suit the load and corrigations has resulted in anything from 22 to 30. Run the trailer axle the same as the rear tyres.
Ran approx 25 in Cape York never had a flat, although I did lose a tyre on the Donohue hwy a few years ago. Unlucky rock turned up from the front tyre sliced the wall open on the rear. Recently graded gravel and no corrigations, running 25 psi and speed no more than 3x psi.
Simpson desert in our trusty 80 with 285/75/16 BFG muddies at 18- 22 psi and kept speed down to under 60 km/h.
As far as the on road pressures, have done experiments at 40 psi and 34 psi. No difference in fuel usage, but much better ride. Better under brakes at the lower pressure but a bit 'soft' on the round a bouts. Have not been able to notice any real difference in tyre wear, but don't drive like Lowdsey.

Rusty.

[mjrandom Out of control poster! Find all posts View Profile Close mjrandom]

http://www.pradopoint.com/showthread...=Tyre+pressure

[sunchaser Member Find all posts View Profile Close sunchaser]

Hi Oldgreyfart,

Is this true?
No, not about your tyre pressures, but about your farts.... Do they really come out grey when you get old?

Oh and yeah don't listen to forums that say not to let your tyres down on gravel. Just go for a drive with them up at road pressure (38-40psi not 28psi) and watch and feel the vibration rattling every bit of your dash and then go the same speed with your tyres down to around 25-28 psi and feel the difference you'll be able to judge for yourself

[OldGreyFart Advanced Member Find all posts View Profile Close OldGreyFart]

Sun chaser. In fact one person who told not to bother was my BIL. I will continue to air down. Btw it justifies the cost of the compressor.

[glen_ep Addicted PP Member Find all posts View Profile Close glen_ep]

Definitely air down for rough surfaces - it makes the drive so much smoother and avoids punctures from rocks.

Surprisingly my tall profile tyres maintain shape even at 20-22 PSI so I tend to go lower for extreme tracks. 20-22 is fantastic for high speed dirt though

From what I've seen the lower profile tyres (such as on the 120's and 150's) tend to bag out a lot around 20 PSI, so 24-26 PSI may be better for them.