Tyre Pressures

[mickq]

Remember, when a tyre gets to its running temperature that you get anywhere between 2 - 5 psi increase in pressure, so you have to be carefull....

I would stick with the manufacturers pressures, sometimes less, sometimes a little more. They aren't completely dense you know, they test each tyre on a load, speed and pressure scale to find out what would work the best as an all round pressure to cope with the application.

Think about it, if your travelling on your own, there is less load on the tyre, less flex under hard cornering etc etc and so the temp stays reasonable and the tyres perform well. If the car is fully loaded, there is more pressure/load being applyed on the tyres so they heat up quicker, stay hotter and therefore will have slightly more pressure anyway which would help carry the heavier load, stop them from flexing etc........

Appart from friction (or lack thereof), physics is on your side when it comes to tyres. Stick with whats recommended and vary it only to the conditions (summer, winter, offroad, etc).

EDIT As a side note, I remember one of the commentators saying that the started pressure for the V8's is something like 10psi, but when running its around 20 - 25.... Obviously the compound of the tyre, and the loads they are placed under, will mean they are much more prone to heating up.... But it just puts things into a bit of perspective.

<{POST_SNAPBACK}>

Unfortunately most manufacturers largely base their tyre pressures on ride. They assume the average Joe wants a cushy ride and doesnt need good handling and doesnt worry about tyres lasting half as long.

That is why they have low pressures. You get a cushier ride. Its a lot cheaper than the manufacturers tweaking their suspension to give you that kind of ride. Money is what drives most of their decisions, nothing else.

I never run a car at the suggested pressures. The only exception would be serious sports cars which know that performance and handling is number one. (And no cars like that are made in Australia).

I certainly would NEVER run at or lower than the suggested pressures unless I am bogged in sand.

For XR6T's I have found 40-41 front and 38-40 rear works well. I usually have a 2psi difference between front and rear (front being higher). In general for rear wheel drive cars you would have the rear slightly higher than the fronts, but the XR6T responds well to the opposite way around. If you do that in an XR6T though (or run equal pressures), it will be OK but the turn in on the car is not as good. Its most noticeable during hard cornering.

The benefits of running higher include:

- Better wet road performance (cuts through water better and more opened up grooves. Especially in aquaplaning conditions)

- Better cornering performance (higher pressure = stiffer sidewall = less flex)

- Better tyre tread life. (Tyre temp doesnt get as hot when its higher pressure, lasts longer)

- Better high speed performance

- Better load carrying performance.

Edited 24/01/05 01:39 PM by mickq