Tyre Pressures in winter

[SAC1]

Check the TPM once the tyres are up to normal operating temperatures. For example after you've driven on a main road at 50 / 60 mph for say 5-10 miles.

[111rdw]

According to the manual the tpm takes temperature into account. So it was my understanding that the fill info will be temperature independent. I think it’s significant it doesn’t tell you what pressure to inflate to but the pressure difference to add or remove.

[SAC1]

From the Good to Know app:

[Toddie]

From the Good to Know app:

Screenshot_20201124-184057_Porsche Good to know.jpg
Screenshot_20201124-184214_Porsche Good to know.jpg

Thank you very much for finding that, it answers all my questions. Somehow I never think to look @ that app.

This just highlights how useful this forum is. Thanks again.

[Tracky]

Interestingly I probably take out about 10-12 psi during the course of the day when in my track car on a warm summer day.

[Tracky]

A change in ambient temp doesn't make a massive difference to pressures. Even a shift of 30 degrees C is only going to cause a pressure change of less than 10%

So a drop of 2-3 psi isn’t to be ignored and for some people could be noticeable too

[Tom 2000]

As stated above the Fill Info screen gives you what is required as that takes the temp at the time of reading into account. If the pressure at 20 degrees one day is correct when the ambient is plus 15 it will also be correct the next day of there is a cold snap.

[jaffacake]

Also worth noting that the tyre fill details can be viewed in the Car Connect app after you've been for a suitable drive.

[jaffacake]

A change in ambient temp doesn't make a massive difference to pressures. Even a shift of 30 degrees C is only going to cause a pressure change of less than 10%

So a drop of 2-3 psi isn’t to be ignored and for some people could be noticeable too

I agree that 3 PSI isn't to be ignored, but you aren't likely to see that kind of change in a warm tyre. TPMS only works after the car has been driven for a while and the tyres are warmer.

You simply aren't going to see a 30C variation in the internal air temperature of a warm tyre. Sure the ambient temp may move from +20C to -10C between summer and winter, but you're never going to see this kind of variation in the warm tyre.

Also worth noting that the "tyre pressure" is actually only a measure of the difference between the pressure inside the tyre to the pressure outside the tyre. The outside pressure varies too. Usually when the weather turns colder, the barometer falls as atmospheric pressure drops significantly. This means the TPMS would read a higher pressure, but the content of the tyre never changed at all. But then the colder temperature helps cancel that change out.

No doubt that a cold tyre sat outside overnight in the winter will read lower pressure than it did on a warm summers day, which is why getting them up to a reasonable operating temperature is sensible before reading any pressures - which is what TPMS does.

[111rdw]

Interestingly I probably take out about 10-12 psi during the course of the day when in my track car on a warm summer day.

Me too. But your putting a lot more temperature into the tyre on track. Never seen melted rubber on my road car.

IMHO you are not going to notice +/- 2or 3psi on the road under normal driving conditions.