Thinking out aloud about tyre failures......

Failures = 1 Simple answer. BRIDGESTONE. Stay away from these @rseholes!!!

The Savero tyres would creak and pop with the sidewall flexing when let down for beach work - didnt sound good. Hardly surprising they both failed (suffered tread blowouts)with very few Ks on them

Yeah OK tyre brand/quality could be one answer but I heard of these types of catastrophic failures in BFG and Coopers and Kellys and Good Year......and so on.

I reckon its a combination of the heat and stress from the excessive flexing. I understand this was one of the main reasons for the tyre pressure sensing devices- after all you can obviously tell when a tyre blows out and you are riding on your rim.

The air tank is a good idea, but be cautious with the setup- alot of compressors do not like starting under pressure and can break valves The best way to go is a pressure switch with a pressure release behind a one way valve, so there is no stress on the compressor after it shuts off, and your air tank holds its pressure.

Previous post covered using spare tyres as a air tank.
volume is about 80 to 100 litres.
Some good suggestions on air hose set ups to.

I think the answer is Yes, I.E A hot day tyres a 15p.s.i driving in soft hot sand, mud i don’t think would cause such a problem as it is a colder temperature and heat wouldn’t build up as much. I think rock hopping in extreme low pressure may cause problems as well.

I think the main problem is excessive heat build up that after time weakens the tyre, then when the tyre is still hot we go and pump cool air into it which in tern my cause the steel belt’s, Nylon/ polyester to cool and contract to fast, repeat that step to many times and something may get fatigued.

Having driven the Coopers over long distances with low pressures 15 to 25psi I can't really say. My tyres do have some serious cuts on the edge of the tread but that could have been anything. I have damaged the inside polyester whatever on one tyre when I hit a rock going very slowly. This tyre has been repaired and is now the spare.

I think that driving at say 80/90kmh with your tyres at low pressures may not be a good thing as you will be exposing more of the tyre to road friction and unneccessary heat build-up which could relate to a tyre failure

It does not take very long to inflate your tyres from say 20 to 35 psi if you have a decent pump. There is however a kit you can buy which will inflate your tyres from the cabin and you will not have to get out of your seat.

But if you are travelling out bush, why are you in such a hurry?

The tyre mentioned(belonging to a forum member) was at the time of the failure run at 28psi. Many made mention of this pressure being TOO low for prolonged high speed running. These comments have stayed with me and got me thinking so I made a few observations(for my own amusement and NOT to try and call BS on any of these explainations) of my own based around them. We went away to Jamieson a couple of weeks ago and I fitted my(and 2 borrowed as I had staked a couple of my own) 31/10.5/15 mud terrains for the trip. Drove to Jamieson via Yea & Mansfield with 38psi in all tyres. After a prolonged period of driving I pulled over and felt the tyre tread and sidewalls for heat. Slightly warm and nothing IMO to worry about, as you would expect. Before we aired down to 25psi on the Saturday, I measured from the ground to the centre of the wheel arch, aired down and remeasured with 10mm being the difference in height. After a weekend of play, I decided to start heading home on 25psi and see how the tyres held up. I couldn't IMO notice any extra heat build up in the tyres after a couple of checks. The tyres were predictable on the black stuff, suprisingly so even when cornering, no visible signs of scrubbing beyond the edge of the tread blocks. I can't make comment on the use/abuse of the mentioned tyre pre failure but I don't think(after my not very scientific experiment) prolonged use at 28psi was the critical factor. I can't help but think that the tyre in question would have failed whether at 28 or 40psi.

As to your question on prolonged low pressure use and sidewall materials fatiguing, I have a mate with a holiday shack near Robe SA and he keeps a Suzuki there for play in the dunes. Its tyres are constantly at 10psi and the many people who stay there drive the absolute hell out of that little machine. After 5 odd years, no tyre failures using remoulded mudders.

OK, that's my 0.02c worth of unsubstanciated opinion/experience

This tyre-topic is timely given that we returned yesterday from Lawn Hill NP where between Charleville and Cunnamulla my Cooper ST (rear RHS) threw a tread. Pressure was, and still is, 40psi.
Why so high I hear you scream - because the Cruiser and KKamper grossed at 4500kgs and I was running at 36F 40R 36 KK.
I use Hankooks for non-off-road "city" use and the Coopers are dedicated for off-road.
The Coopers had done 30,000kms, all "off-road" (that is, including bitumen between home and "there" to get off-road). Previous trips had been the CSR plus Cape Leveque, Karrijini, Chichetser, Kalbarri, Esperance etc over 3 months in 2003, Flinders R in 2004 and now Lawn Hill. Hardly rough tough off-road although for the CSR we ran 18F, 24R, 18KK including the rocky sections (lazy).
Rear tyres on the LC had chips etc and signs of wear from the rocky sections of the CSR but otherwise were in great condition and with very even (lack of) wear.
I will see Mr Cooper tomorrow and see what the situation is with the ruined tyre. The other tyres appear to have a million kms of life left in them.

hi guys
dont let your tyre pressure down on dirt roads keep the pressures up at speed , if you have 25 lbs dont go over 60 ks it will generate heat and blow out your tyres your ride if you have a leaf spring will be softer if you let your tyres down but there is a down side you must travel slower believ it or suffer

I have had Cooper 35's on the F100 for the last 4 yrs and apart from staking the wall
on one of them near Tilpa have not had any problems.
Also I run them at 24lbs all the time.
Even when towing the van [33ft Viscount] which weighs in at 2.75 ton or loading the ute to the gills, so much so that it went down 4 ins over the drive and towing a loaded furniture trailer from Brisbane to here another 3 ton the Coopers have handled it all.
Charging around the back blocks when I was contract header driving or poking about in the suburbs nothing fazes the Coopers.
Any more pressure and Effie rides too rough. I know this reads a bit like an ad for Coopers but its not, I just can't follow the logic of this 40-50 lb stuff or this Yankspeak [airing down or up] , you either let some air out or you pump them up!
40 yrs of driving trucks on dirt and rock or whatever other sh-t the local council decides to throw on the ground gives me some idea of what does and doesn't
ruin tyres.

Maybe a tyre monitor would help i believe they tell you pressure and temperature.

I had a set of BFG all terrains which did several thousand kms at 18-25 PSI some of it not that slow ie: on a trip to cape york I dropped the pressures at the gulf (lawn Hill) 24psi and never pumped them back up until we were in Cairns (three weeks later), in some sections we were doing road speeds (ie: cooktown to Cairns).
The same tyres did several trips to the Vic High country and also some sand and odd trips...
The tyres lasted 95000kms.
When they were removed, I took one to a friend of mine who is now retired but an ex tyre manufacturer and we inspected it together, he cut a section and checked it all out, he said all OK other than the wear on the outside of the tread due to low tyre pressure. The tyre in question had been deformed (negligible but he found it) in some sections due to bruising (that is what he called it) and believe it or not, he said that it could possibly be an impact when the tyre was at high pressure.
I calculated that those tyres would have travelled about 50% of their time at 25psi or less, the rest at between 35 and 40psi (road pressures).
Never had a puncture.... but lots of cuts and chunks missing

I believe that sort of major tyre damage usually happens because brakes are applied when a puncture occurs. This puts huge forces on the sidewall.

I've been a fan of low pressures on outback roads. Usually run 25psi at up to 80 kph, and 20psi at up to 60kph. No punctures in 6 years and heaps of trips.

Cheers
Phil

Wish I knew the answer - had 2 tyres go on the black stuff over the last 2 years on the Troopy - both at the manufacturers recommended pressure.

Both tyres were 2/3 worn so I was not too upset as they were near their use by date anyway for off roading.

Tyres were Bridgestone Desert Duellers.

Stevesub

A quality tyre with sturdy walls will take more sustained heat, but there are limits. As Willem says, why so much hurry. Have break while you reinflate - and, there is no law against stopping from time to time and going around checking the tyrewalls by hand - if they are warm to warmer, ok, but if they are too hot to leave your hand on, you are in trouble - you'd need to up the pressure a bit and slow down. The last tyre I saw a tyre shredded on a car it was litterally too hot to handle - it was damn near rubber meltdown - in my view, the culprit was overloading - that plus speed = too much heat.

lower tyre pressure off-road are not just an advantage for tyre life but also stop the sh*t being shaken out of vehicle components which can result in leaking aircon, power steering systems etc...

I notice a lot of people with stuffed tyres run at low pressures which I too am an advocate off. Where I see the problem is they are usually overloaded and travelling too fast. when they hit a washout the rim compresses the tyre even more and I suspect the rim may even cause the initital damage as it bottoms out. I have followed a few in this situation and you can see it almost in action happening before your eyes. The answer Slow down.

I think it is excessive heat that causes sudden separations/blowouts.
Excess heat is produced when the tyre is deformed and rotating too fast. This is the same process that causes wire to become hot when you repeatedly bend it in order to break it. Deformation occurs with low pressures and excessive loads. If you travel slowly there isn't enough internal friction to generate heat. In cool conditions heat build up is dissipated to the road and atmosphere. I've found that black bitumen in high sunshine can cause amazing tyre temperatures compared with the same load/speed/pressure on cool road surfaces. Tyres can become too hot to touch.
In summary, if you are overloaded or running low pressures (lots of side wall bagging) travel slowly. If you are driving on hot bitumen be aware that thermal build up is likely to occur. High speeds and heavy loads could result in catastrophic failure.

OK let me see if I have the general consensus right. Low pressures and too much speed cause increased heat...and over time this leads to tyre failure. So how fast is too fast for say 15psi, 20psi, 25psi, 30psi etc? I suspect that most people lift the loud pedal when they drop pressures but from the foregoing discussion it would seem that many people think that they probably don't lift it quite high enough. Gotta say that I didn't expect this topic to attract so much attention but it is interesting to get the variety of viewpoints. Also good to see that the majority of people didn't use it as a forum to bag tyre brands.
Thanks for the input everyone.
Cheers
Pete

From reading the discussion it almost seems like a rough guide would be :
Below 25psi, double your PSI to get max cruising Kmh for rough roads.

Hi Pete,

This is an off topic reply. I've just sold my '99 GU 2.8 and purchased a '03 GU 3l. The new rig is in need of a set of tyres. Had Cooper ATs on the other Patrol but suffered all the usual wobble problems. Was thinking of Coopers (ATR) again but now looking into the wobble issue some more. Talking today to a tyre guy who reckons that the issues on Patrols really arise from LT tyres, with their stiffer construction exacerbating the inherent Patrol problem. I don't want another 3 yrs of wobbles!

Given I don't do lots of extreme offroad work (mainly beach, touring and frankly speaking at least 80% on bitumen) I don't think I need LT tyres. I am interested in Bridgestone D694 and Yokohama GO11+II (my brother in law has these - OK). Anyhow, notice on forum search that you had the Yoko's fitted to your Patrol and were really impressed with lack of wobble, noise, etc. I was just wondering how these have worked out for you and if you would recommend them. I was hoping you could send me an update to hcarlisle@orbitalcorp.com.au

Thanks in advance,
Hugh