tksingh

ok, I have searched - no real answers... it is winter in Toronto, temperature about freezing to slightly below. In the mornings my pressure shows about 31/37 and then warms up to 35/42 or so after some driving. I have the TPMS set to partial load. I get no warnings but when I put it to the screen that shows +/- I get +3 and +4 on all 4 tires.

So is this because if reference is for 33/39 at 68 F, they should really be about 28 and 34 at 30 F ? (approx -1 psi for every 10 F), in other words the TPMS takes into account the lower temp and still wants it to be 33/39 at 68 F? Or should I say screw it and make the tires 33/39 at even these cold temps and ignore the TPMS?

Sorry, got the car this winter so I do not know what the pressure was when it was warmer.

In addition they are 19's (All seasons actually, could not find winters in stock this year...)


Advice??

cheers
Ken

Le Chef

At 38F outside your tires will be reading 30F & 36R. Which means you should inflate your tires 3lbs all round to compensate for the temperature drop. So back in your heated garage which his at 68F your tire pressures would go up to 36F and 42R.

tksingh

thanks. I will add some air I guess, but I do think that the TPMS system is taking into account the temperature at cold and is set to calculate your psi from 33/39 at 68 and expects your psi to be less when it is colder...

mdrums

Check the owners manual...Porsche explains how ambient air temp affect tire pressure and there is a graph to go along with this.