Thread: Tyres out of round

age would be your biggest enemy.....

I agree with Sprint that age may be a problem.

However it could be due to a few things. I use the 4psi rule in my bus and it proved invaluable on a trip around oz (no punctures in 45,000kms around oz with coopers!). Essentially your perfect tyre pressure is 4psi higher at proper operating temperature. For example on rough gravel roads say, let your tyres down to 26 front and 32 rear. Drive for 5 minutes. Re check pressures. If the front is at 30psi and the back 36pse (ie 4psi higher), you are at the perfect pressure. This theory applies in every application. It can take a bit to work out all pressures for all conditions but I worked out soft sand, sand, slow gravel, fast gravel and road psi's. Unfortunately they will differ for each vehicle and the load that you carry.

Another reason could be tyre injury. A mate of mine runs his tyres at extremely high psi to avoid punctures on sharp rocky roads. He then had two tyres explode within 20 kms of each other at highways speeds later on. My theory was that with such high pressures in the tyres the steel belts were dented or deformed permanantly (rather than deforming and then reforming if they had of been at a lower pressure) and then when heated up to operating temperature later on, the tyres developed a weak spot at the point of injury and exploded. Your tyres may have gone out of round due to tyre injury perhaps

Or your tyres could be part of the dreaded cooper batch from around 10 years ago that start to de-laminate. There are many threads on this topic on many forums . I for one, have never had a problem with cooper tyres.

Also, if your wheels are out of balance (are they steel wheels?) they can cause tyres to become out of round. It is essential with heavy tyres like coopers to get them balanced and rotated every 10,000 kms. Same applies with other heavy brands too such as bf's etc.

Originally Posted by gusthedog

A mate of mine runs his tyres at extremely high psi to avoid punctures on sharp rocky roads. He then had two tyres explode within 20 kms of each other at highways speeds later on.

According to the Tyre Pressure Guide written by the bloke at the Pink Roadhouse at Oodnadatta, tyre pressures (and speed) should be lower on rocky roads, not higher.

Pink Roadhouse - Oodnadatta Track (South Australia)

He insists that high pressures are responsible for the majority of failures.

There are other 4WD sites that agree with him.

Originally Posted by Sprint

age would be your biggest enemy.....

Not at 6 years. I've bought tyres new that were 5.

How does the 42psi used compare to the max inflation pressure of those tyres?

Originally Posted by vnx205

According to the Tyre Pressure Guide written by the bloke at the Pink Roadhouse at Oodnadatta, tyre pressures (and speed) should be lower on rocky roads, not higher.

Pink Roadhouse - Oodnadatta Track (South Australia)

He insists that high pressures are responsible for the majority of failures.

There are other 4WD sites that agree with him.

Agree obsolutely vnx205. This mate of mine disagrees though and sometimes you can give people all the info in the world and they'll still make whatever decision they like regardless

Cheers,