Thread: Off Road Tyre Pressures (was Kookynet...)

Originally Posted by TheLowRanger

am currently living in Derby and driving the GRR is a weekly occurrance, so I do have some experience, but each to their own.

Jeez, where were you when my daughter was trying to give away a Disco spare wheel, fuel and water jerrycans, and camping gear last week before moving back to Sydney from Derby (she was a nurse at the hospital)?



Ron

can u still rely on Len Beadell advice he was using tyres designed and manufactured nearly 60 years ago

on recent 4wd training course the view of the instructors ex-army were leave trye pressures alone until you need to gain transaction in sand by lowering

yes lots of clubs advise lower tyre pressure on gravel roads and tracks but where is the evidence that justifies this and could it be another urban myth.

sand beaches l always drop to 18 lbs or lower depending on traction requirements for a day's outing

note when people talking about lowering tyre pressure for heavily loaded vehicle they rarely discuss whether the heavy load is something that would be better off reducing or spreading over vehicles in convoy or splitting between vehicle and trailer.

My opinion for what it's worth is that tyre pressure should be adjusted for different surfaces to improvve the handling of the car as well as absorbing shock and stopping increased tyre wear/punctures and stake resistence.

Sand and mud is easy, around 15psi, same can be said for rock crawling.

The hard one is long distances on gravel roads, this is more of a drive the car and see, because (and this has been my experience only i'm talking) not all dirt roads are the same.

The pressure you have set for the GRR for instance may not work on the Birdsville track, also what feels good for you may not feel good for me, so don't just set pressures to what your mate reckons they should be, work it out for yourself.

I tend to adjust my pressures to how the car feels, weather conditions can play a part too and how much weight your carrying as well, feel the tyres after a long haul, check the pressures to see if they have increased, if they have, then by how much, you can soon tell if your pressure are too low, your pressure will have increased alot if they are.

Most important is slow down on dirt roads, anyone who sits on 100k plus on dirt roads in a 4WD is asking for trouble, especially if you have lowered your tyre pressures.

Baz.

As someone has mentioned previous when Len was doing his driveing was 60 years ago, tyre compounds have advanced light years sence then we used to teach only drop presures for traction, spred the load over the convoy, and on sand, we have gone as low as 12psi in a loaded LRPV hard rocky flint type tracks as high as 50 psi same vehicle,

just my 2 bobs worth


Tony

simple....

as you lower your tyre pressures you lower your speed

The military used to have a data plate that gave onroad (black top) offroad (gravel tracks and the like) and a sand an mud pressure.

For the 110 (non power assisted)

32psi for on roads
24psi for off road
18psi for sand and depending on who your teacher was
10psi for emergancy soft

they also used to list a maximum reccomended speed (and this is all from memory)

100kph for the road
80 kph for off road
40kph for sand
10kph for emergancy

Its not bullet proof and its not the absolute will get you out of every possable situation but its a good starting guide if youve got nothing better to go with.

I have always been of the understanding that lowering tyre pressures on roads like the GGR laid the sidewalls out and exposed them to rock damage. I have always kept them at highway tyre pressures to keep my sidewalls upright and let the tyre treads do the work.

Also, drive to a sensible speed to reduce heat buildup and not go too fast and drift the car around corners. Again, any drift will expose your sidewalls to rock damage.

On the GGR I have been passed by many speeding 4WDs, only to pass them later on changing tyres by the side of the road.

as it is not my practice to endorse any information posted in this forum by any other members, i am finding it very hard to cough up the following statement. i would also like to apologise to anyone who hasadmired my stance on this policy.......well, here goes;-
my findings on high speed dirt roads are that if the surface is as hard as a paved road, you should be running road pressures, especially if you are carrying excessive load, as you would for an extended outback trip. on a trip in 202 via simpson, oodnadatta, diamantina road, mereenie loop etc, 5 vehicles in the group of 6 ran around 45psi and got no punctures in 4 weeks of outback travel, one vehicle was running 32 psi and got ten punctures. all of them in the middle of the tread and we all had BFG muddies on. he was running a lower pressure because he was riding on 35" x 12" tyres which had a different load rating and a max press of 36 psi. they were overloaded and bagging heaps as a tyre would if let down for medium consistency sand.
in conclusion i have to aggr...agge....agri....agree with roger.

I find that normal Hwy pressures for everything other than very soft sand.

For me, that's 60psi rear and 42psi front (Michelin XZL).

I have also observed that people who drop the pressures for dirt & gravel tend to have multiple punctures.

M