Tyre pressure difference when wheels are hot/cold

[Orablue]

Hi

 

The recommended tyre pressure for my car is 220psi.

 

I believe that this is the pressure when the wheel is cold. However, the wheels are normally warm when I pump the tyres. Therefore, pumping in 220psi when the wheels are warm may not be equal to 220psi (in fact lesser right?) when they are cold.

 

What is the pressure difference could it be?

 

Is there a rule of thumb method to compensate for the difference in the temperature when pumping the tyres?

 

Or the difference is so little that we don't have to bother... ;-p

[Roboto]

The difference is about 1 psi for every 5 degrees Celcuis.

Problem is finding out the temperature of your tire when you are pumping.

Usually I check my tire pressure with a gauge before I drive to pump air.

Then check again when I am pumping.

 

Also your tire pressure should be 220kpa, that is about 32psi.

[BMW320i]

220 psi !! kpa you mean.

 

My front requires 230kpa which is about 33psi but some how the reading indicated 234kpa instead. Marginal diff is alright.

[Soya]

rule of thumb: pump 2psi higher if tyres hv warmed up.

[Orablue]

oops! its kPa not psi!

 

pai sey..

 

so rule of thumb is add 2psi for warmed up tyres...

hmm... that's about 10-15kPa more

 

wow.. i've been under inflating my tyres... no wonder my old G9 corolla steering was "heavy"... haha