Tyre Pressure on corrugated bull dust

[Racoon Lurker Find all posts View Profile Close Racoon]

I am running Bridgestone LT AT tyres. On a recent trip on development road out of Boulia (about 800 k of corrugated dirt and bull dust) I was still shaking some days later. I received various advice as to the appropriate tyre pressure. Some said don't drop the pressure from the black as it would expose the tyre walls to puncture. I took this advice and found I was unable to exceed 60kph and shook all the way. I noticed others seemingly travelling at much higher speeds without much difficulty. Is there a planing effect at higher speeds reducing the shakes? Are higher speeds and comfort able to be achieved by reducing tyre pressure? Any advice?
Racoon

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Re: Tyre Pressure on corrugated bull dust

About 24-26psi is good tyre pressure for dirt roads. But you can't go at high speeds then (high to me is 100km/h). A good combination of tyre pressure and speed will give you the most comfortable ride. Running road pressures (to me this is 40psi) is very uncomfortable and the suspension is doing all the work. Dropping the the pressure makes the tyres mould around the corrugations but you need to slow down to an appropriate speed as well.

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

Re: Tyre Pressure on corrugated bull dust

As AMTS said, definately drop your pressures, somewhere in the mid 20's PSI depending on your load. A good rule of thumb in regards your speed is, 3 times the PSI, so if you run 26PSI your maximum speed should be 78km/hr. Not only will lower pressures give you a better ride and reduce wear and tear on your car it will also dramatically reduce your chances of tyre failure.

Cheers Andrew

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

Re: Tyre Pressure on corrugated bull dust

Bugger... just drafted a post and then my post timed out.

Anyway... when we did the Oodnadatta Track last year we ran 28 psi on all tyres, Prado and 4wd camper trailer. We kept our top speed below 85kph and never had one problem. The car and trailer handled perfectly.

You really do need to manage your tyre pressures depending on the road surface and your usage. But you also need to watch your speed. I never understand why some people travel way too fast on dirt. You get away with it for a while, but when things give way, then you're in big trouble. There are way too many variables on a dirt (read loose) surface to be travelling at over 25 metres per second. Better to maintain a slower, but more constant speed, and enjoy the journey. Hell, you might even get to enjoy the experience rather than driving on the edge of your seat all the time. And take the time to look out the window and take in the views and experience of travelling across this beaut Country of ours.

Cheers. 8)

[dereki Member Find all posts View Profile Close dereki]

Re: Tyre Pressure on corrugated bull dust

I read somewhere that doing about 80+ on corrugations will allow that car to skip over the corrugations, instead of going into each one.

There is a little write up about different road types here. They say 85 is best, but then say bulldust is dangerous so do it slow, as it hides any large holes in the road.
http://www.exploroz.com/OntheRoad/Skills/4WDSkills.aspx

D

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

Re: Tyre Pressure on corrugated bull dust

As they others have said drop pressure and speed. if going into a dip then drop speed even more but lay off the brakes twoards the end to allow the front to raise to stop the front hitting hard if you have too much speed still.

[Racoon Lurker Find all posts View Profile Close Racoon]

Re: Tyre Pressure on corrugated bull dust

Thanks all for advice. The common theme is reduce pressure not only in the tyres but in the cabin.

[Whitey1 Advanced Member Find all posts View Profile Close Whitey1]

Re: Tyre Pressure on corrugated bull dust

And dont forget to stop occasionally to let your shockies cool down! That makes a big difference.