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

Originally Posted by p38arover

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

Ron,
I have only recently moved here to Derby. My wife is a midwife at the hospital for a 6 month stint. I actually met your daughter at her farewell (Lindell if I recall correctly) as it was also the farewell of one of the midwives. I put 2 and 2 together and picked her for driving the other Disco in the carpark and thought it may have been nice to get to know her a bit better if circumstances were different. I hope she had a safe trip with her adopted cats and tell her that Glen and Emma say hi, and that Zeke and Elijah (my 2 boys)want to know how the cats are doing. By the way, what did she end up doing with the bits and pieces?

When I was at the Oodnadatta pink roadhouse they had a sheet that mad tyre pressure recommendations for the oodnadatta tk based on their experiences - I'd assume that they know something about pressures and dirt roads considering they live on it and repair tyres all the time. Its a fast and stony track.

They say that split rims and tube tyres are the worst performing, and least reliable with a rec pressure of 30F/36R for a Cruiser.

15, 16, 17" tubeless loaded big 4WD 20-24F/26-30R
10R15 109 rated max reliable pressure 26psi on dirt.

Campers - 20psi

15" tubeless loaded big 4WD 20F/26R
15" tubeless unladen big 4WD 24F/24R

They also say that:
Most wide 15" tyres need low pressures.
The most likely overinflated tyre to fail is the left rear.
Sidewall road impact does not increase at lower pressure.
Use 4WD on dirt roads at all times.
At 30psi on dirt a 109 rated tyre is unreliable, a 114 is reliable.

The suggested pressures are for high load, high speed cruising on low grip dirt surfaces and ock or sand.


Here is something interesting from Cape York, which didn't appear to be overloaded.

Look at the tyres,
Look at the tyre pressures,
Look at the axle!

IMHO, if you're driving offroad, drop the pressures.

When I was at the Oodnadatta pink roadhouse they had a sheet that mad tyre pressure recommendations for the oodnadatta tk based on their experiences - I'd assume that they know something about pressures and dirt roads considering they live on it and repair tyres all the time. Its a fast and stony track

.

Strange, that with those recommendations generously advertised that they "repair tyres all the time" - then again they are running a business and more tyre repairs means more income and bigger bottom line!

Originally Posted by TheLowRanger

By the way, what did she end up doing with the bits and pieces?

hello Medling mob! my dad just shouted at me that you all said hello, i just thought "how does he know them?!"
you can tell the boys that the cats are well and i'm sending lots of hugs to both of them! i hope you and Emma are doing well up there, you can tell Emma that Kelly arrived safe and sound on the farm.

as for the parts - the car transport company said they were 'part of the car' and let me send it all off.

look after yourselves and God bless!

- Lyndal

Originally Posted by Slunnie

Here is something interesting from Cape York, which didn't appear to be overloaded.

Look at the tyres,
Look at the tyre pressures,
Look at the axle!

IMHO, if you're driving offroad, drop the pressures.

Hell Slunnie, what is that with the rigid rear end doing an impersonation of an independent rear? Thats scarey.

From my admittedly limited experience I've found its important to keep in mind that a drop in pressure should also involve a drop in speed.
Steve

Originally Posted by Xtreme

.

Strange, that with those recommendations generously advertised that they "repair tyres all the time" - then again they are running a business and more tyre repairs means more income and bigger bottom line!

Yeah, I thought the same. They probably give tourists that are already at Oodnadatta and can only drive away from their location a tyre guide to make them some money from repairs hoping that they return for the repair despite that this may very well cause a major accident and quite possibly kill people. All of that country good will and community spirit really has vapourised into money making ventures.

Or perhaps they have learnt from experience about what actually works and want to help people out. Interestingly, I spent a fair bit of time chatting with the Mickey Thompson sales rep who was at the LROC show, and he said the exact same thing re tyre pressure - except that he also said that as pressures drop, so should speed to keep the heat out of the carcass.

I tend to think that experiences can yeild multiple and conflicting results, and that we really need to see all of the info, eg, the 35 that kept puncturing... it may not have been that it was a 35, or that it had a low pressure, or that it was bagging. Perhaps it was too close to the max load, perhaps it had been previously overheated, perhaps the geometry was scrubbing etc etc etc. PErhaps the other vehicles didn't have punctures because the rough tracks were rough but not piercing.

On the flipside, somebody else has found the opposite because etc etc etc.

I doubt very much Oodnadatta are giving information out so that they can make more repairs, and likewise I doubt Mickey Thompson give out the same advice so that they can give their tyres a bad name. Most tyres these days are probably just very good and are built to withstand the abuse they are given and have load indexs well beyond what they get used for, giving extra margins for safety.

Originally Posted by shinz

Hell Slunnie, what is that with the rigid rear end doing an impersonation of an independent rear? Thats scarey.

From my admittedly limited experience I've found its important to keep in mind that a drop in pressure should also involve a drop in speed.
Steve

Gday Steve,

It was frightening to see and it looked like it failed suddenly for the driver. We stopped to see what/where was going on but the owners had gone already. I think it was just high pressures and relentless corrugations that had taken their toll on the vehicle. I'm not sure how many km's the Pajero had on it. On the flip side, every 4WD in our group ran 20 or 25psi in our Simex's and drove all over Cape York smoothly and without any dramas at all.

Not sure now where I got the information but it was that the hot temp of your tyres should be 4psi above cold temp. Using that info I ended up using 25psi on a rangie going to Cape York (no punctures). Using this rule means if you travel slower you use lower pressure. With heavier loads your pressure is higher. The advantage of this rule is it covers most vehicles and terrain. It has worked for me so far, touch wood.