Tyres GRR & Tanami

Mate, Disco's don't die ..they just have issues.

Thanks, that's about what I was anticipating. Planning to drop pressures by about 20%.

Hey Smudger

A mate of mine runs tours across the GRR monthly, He runs his tyres at 42 psi he has between 2 to 6 pax and tows a trailer full of camping gear.

I have 4 cruisers that do the Jim Jim road daily, which is the same corrugated type of road as the GRR.

That means my trucks do 700km each per week on this road, I run my tyres at 40 F and 42 R neither of us have a problem with tyres blowing out.

IMOA lowering tyre presure on this type of road is asking for trouble.

Cheers Steve.

I hear you Steve,
But my truck spends 90% of it's time in Sydney traffic, so I run ATs. I'm guessing that your trucks have more aggressive rubber. Having said that, in the good old days when we did the Nullarbour in our Holdens with pretty basic radials, we never let the tyres down. And the only problems I had was picking up the tacks that the servo's used to drop on the bitumen roads as you came into town. Never lost a tyre on the bulldust, and crossed it 5 times before they sealed it.

Hey Smudger

I run OZ made D693 265/75/16 bridgestones.

Steve.

Yep, I'm with Steve - 40-odd PSI. Higher pressures will reduce the chance of sidewall damage due to bulging and prevent too much flexing in the carcass tread area.

If you don't want sidewall bulge then don't use radial tyres, fit x-plies.

Radials are designed to flex in the side wall and over inflating negates this. Radial tyres should be considered as being part of your vehicles suspension system and are designed to help give you a comfortable ride but don't do this if over inflated.

That reminded my of a convesation I had with couple of roo shooters at the Middleton Pub a couple of years ago. They told me that they run XPly rags at 70psi. True story ..they told me, "Ride's a bit rough, but they're so bloody hard, even gidgee stakes can't get through 'em."

But it comes back to the point that if you dont want a puncture use higher inflation pressure to reduce sidewall bulge...pretty simple stuff really. On BFG AT's 42psi is not the upper limit either so it's not like they're being overinflated.

Besides, who runs xply's on 4WD wagons?

www.beadell.com.au/tyre_construction.htm <<some good info

Hi off-track,
To quote from your link to Beadell Tours;

S.B.R 4WD tyres are the best compromise for On-road and Off-road work. Steel plies under the tread of the tyre give strength and rigidity for high speed On-road travelling, while also giving the ability to bend and grip reasonably well while Off-road.
The sidewalls are thin and supple, allowing little heat build-up at high speed thus reducing tyre wear. These same thin sidewalls can also be used as shock absorbers for Off-road. By letting your pressure down a few psi, the tyre will absorb many of the corrugations and potholes with ease. Most importantly it should reduce the risk of damage, as the tyre with less pressure will "give way" so an object won't damage it, (try popping a half flat party balloon). This makes travelling much more comfortable and less strenuous on the suspension and chassis of your vehicle.
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I agree with what they say. Don't run tyres so hard that the side walls are firm, and, they give both you and your suspension a better ride.

What 4wd uses x-plys ? I reckon I would have more chance of getting a x-ply tyre for a Troopie ANYWHERE in Australia then you would looking for a radial (note I say ANYWHERE). But that is not the point, I am not saying you should use x-ply tyres. I am saying that you should not run radials so hard that they have a rigid side wall.

Ahh yes but I did say '4WD Wagon' for that very point. ;-)

Staking damage through the sidewall is more risky through underinflation where the sidewalls balloon out than higher inflation where the sidewall is flatter. This is the point that is being discussed.

You are indeed right to say that lower pressures increase comfort but that means little when the tyre has been punctured through lower inflation pressure. Of course the opposite spectrum to this is absolutely rock-hard tyres rattling the crap out of the vehicle but this would be no more than if x-plies were fitted.

And again you are right in stating x-plies are the preferred option in rough terrain where punctures are at risk but the tyres being discussed are AT's so the best outcome (apart from fitting x-plies) is to inflate them to around 40-42psi, not deflate them. (Without looking at them I believe the quoted upper limit is around 65psi for BFG AT anyway)

Hi again Off-track,

I go along with everything except the pressure. Actually I hate x-ply and leaf springs, but, horses for courses. I will stay with 26 -28 psi and enjoy the scenery :-))