Tyre pessures

[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]

Originally Posted by 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.

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.

[robertodonnell]

So how did someone come up with 4 psi as the golden number?

Sent from my D6653 using Aussie Jeep Offroad mobile app

[NTRubicon]

Originally Posted by robertodonnell

So how did someone come up with 4 psi as the golden number?

Sent from my D6653 using Aussie Jeep Offroad mobile app

It's probably 4psi as that is much easier to divide into parts than any other number. 1/4,1/2,3/4 = 1psi increments

This is likely to relate to the same reason why the imperial measures system is designed the way it is and 12 is their magic number for measuring.. Easier to divide without breaking things up into repeating decimals (1/4 of 12 is 3, 1/3 of 12 is 4, and so on.)

(Extracted from another website)
Use the tyre placard as a start point, drive for an hour, stop and check the pressure. If it's gone up by MORE than 4psi, your start pressure was too LOW, add pressure now! If it has gone up by LESS than 4psi, then your start pressure was too HIGH and youn need to drop 2psi NOW! Those new pressures should be used as your start points for the next cold start!

And when you are off-roading, then use it the same way. Start with the guidelines that come from places like the Cooper Tyre Book, the Mickey Thompson guide to tyre pressure, even the prado4x4 guides above. Apply the 4psi rule, and adjust your pressures as you go. You will take only a sort while to work out what pressure is a good start for you, and by using the 4psi rule you can adjust the pressures to what is the optimum for YOU and your driving style, load, vehicle, conditions, temp, etc.

[rang0]

[QUOTE=robertodonnell;1572502]I just replaced the tyres with Nitto Terra Grappler A/T 245/65/17 on my WH. Not impressed with the tyre shop as they've put 43 psi in 3 of them and 48 in the other!

Are you for real? You must be very hard to impress if you not happy about air in your tires:what: