euan

I usually notice a 1-2 PSI variation on either my SO2s or my Ultragrips.

I had checked mine first thing on a cold morning on sunday before going to a meet, and once warmed up they were far too high. 2 PSI more than C7BLE with the same tyres, who had set his to the same level as me before the meet, but probably on the evening before.

You could try other car forums - I was speaking to an MX5 owner before xmas who was running Proxes.

andyds2k

According to AVON tyres 5 to 6 degC drop will result in 1 to 2 psi drop in tyre pressure.
So for those up north your tyre pressures are too low.
In the south your tyre pressures are too high.

So it begs the question, when the manual says check your pressures when the tyres are cold, what does cold mean

I would hazard a guess that tyre pressure should be set at STP (Standard Temperature and Pressure), but this is 0 degC and 1 atmosphere pressure. Damm difficult to find here!! Or is it based on "standard state" temperature of 25 degC.

As you can see what you will never achieve optimum setting of tyre pressures when the tyres are "cold" as the environment temperatures vary too widely to achieve this, unless you have a temperature controlled environment. Also, trying to set tyre pressures to anything better than 0.5 psi is just wasting time.
32 psi set in winter will not be 32 psi when it comes to summer, hence check pressures regularily. Also try and set the pressures at different times when the outside temperature is almost the same (not always possible).

This is all confusing and I think its all

Welshman

I think anal is the word you were searching for!

AquilaEagle

Use nitrogen, it is less sensitive to temperature change Not many places you can get it, but they do it at Costco in the USA!! (at least, at the one in Escondido anyway)

mikey k

Just done a 1st Lotus day with them at 33.5 psig, too low need an extra couple of psig to make the break away more predictable. Made a big difference on Moff's car!