Wednesday, Oct 29, 2014 at 13:35
Actually I do not believe the tech specs and the measurements go out the window in the bush......ya simply "can'a change the laws of phisics, Jim"
If the
tyre fails...the tech specs will usually tell you why this has happened.
If the tech specs and measurements would have been heeded in the first place many of the
tyre failures simply would not have happened
The single biggest problem with tyres on touring 4wds is.....people fail to pay attention to the tech specs and all to frequently run the tyres overloaded, under pressure or otherwise outside of the spec.
When you look at the tyres used on many 4wds.....they are being operated right up in the top end of their load range
take for example the factory 7.50R16 8 plies that come fitted to 70 series.
If a 70 series ute is loaded to capacity it is necessary and specified to run 65psi in the rear tyres......I have a set of
dunlop road grippers in the yard off a new 70 series.....the maximum pressure stamped on the
tyre is ...65psi.
So they are right at the very top of the load range and pressure.....in essence maxed out.
so they have to be run hard.
The tech specs and the measuremenst tell me that if a larger, higher rated
tyre was used.......one that must have more air volume......it could be run at lower
pressures.
Thus
less ground pressure....even when fully inflated to highway
pressures
more latitude and safety margin all round.
now here is a thing many wont have observed......load V pressure performance of tyres is not linear.
In the middle of the load range load V pressure performance is pretty well linear.....but toward the top and the bottom of the acceptable load curve the performance gets non linear.
Up the top of the range more pressure is required to get an increased load capacity....at least that is my observation having graphed a few load tables.
So like everything.....if we want a
tyre to work well and reliably, we need to be running it in the mid range of its capacity.
tyres natually have a self protecting mechanism.....when they get hot, the pressure inside the
tyre increases thus tending to reduce the stress on the
tyre......it balances and equalises.....unless you push things too far.
If you have a
tyre running hard and right up at the top of its load range and iat its maximum pressure and still it is getting hot.....where has the
tyre got to go but beyond the pressure spec.
The specs and the measuremenst tell us all this before we even turn a wheel.
The tech specs and the measuresurements confirm the experience not contradict it.
cheers
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