Tyre pessures

[wilsonjeep]

I run a bit more in the front left because I drive roundabouts a lot and they KILL front lefts!!! 36 and 40 front left!! Keeps the side lugs off the road a bit more!

[robertodonnell]

Tyre Pressures

Well I did find the placard in the glove box, and was surprised that is specifies 33 psi on all four corners!

Anyway, I set all at 37, we'll see how we go.

Cheers,

Robert

[07commander]

wow i have never looked at it, i follow the 4psi rule and i run 45 front and 40 rear.
I use to run 40 all round before i tried the 4 psi rule and the front started to wear bad on the out sides.

[robertodonnell]

So with the 4 psi rule, if the tyre is under inflated it won't rise by 4 psi when the tyres are hot, and if it's over inflated it will rise by more than 4 pound?

[Clarky]

No, from cold if the tyre increases in PSI by more then 4 psi it can be either over or under inflated. Its a balancing act.

An under inflated tyre will heat up far quicker then an over inflated tyre.

I suggest you put in 33psi (the factory recommended tyre pressure) & go for a half hour drive & check your pressures. If the pressure has increased by more then 4 then I would put a few psi more in & repeat.

You should only adjust tyre pressures while cold so over a week or so you should figure out what's best for your brand of tyre & driving style.

[robertodonnell]

Thanks Clarky. A bit of a black art there.

[07commander]

yes what clarky said is right, when under inflated you have more tyre in contact with the road which crates more friction hence more heat which will increase the pressure more.

It sure is a bit of black art but once you work it out then you know what to run and when you replace your tyres if they are similar the pressure is will be similar.

I run Mickey Thompson a/t's and done 80k on them, they still have about 30% tread on them, but in saying that it's easy to monitor tyre pressure with a tyre pressure monitor.

[JamesLaugesen]

yes what clarky said is right, when under inflated you have more tyre in contact with the road which crates more friction hence more heat which will increase the pressure more.

Just splitting hairs, but the majority of heat is generated in the flexing sidewalls, surface friction is pretty-much negligible (so you can still overheat an under-inflated tyre on loose dirt/mud.). Less pressure = more flex. Thin/softer sidewalls mean a more pronounced effect and vice-versa.