AlexKeyWest

My C43 and other cars I own here in South Florida lose air pressure overnight if it's abnormally cold. We all know PV=nrT. What surprises me is that as the day warms up to normal weather the air pressure stays the same and doesn't go back to where it was. Why?

sdrutledge

I suspect your idea of "abnormally cold" and "normal weather" is very different than mine way up here in Canada, but that is not what I see. Overnight temps drop pretty low here, but we also get some pretty warm days. My tire pressure seems to fluctuate pretty consistently. Maybe you have a leak?

superswiss

Yeah that's not what I see, either. I live in a mild climate as well here in the SF Bay Area. At night, temps drop into the low 40s and during the day they are in the 50s and 60s at the moment. My car is garaged and the temperature in the garage pretty much doesn't drop below 70 and that's where I usually adjust my pressure. So if I'm out at night like this past weekend, the pressures drop as expected, but they go back to normal as the tires warm up while driving and also after it's parked in the garage and everything warms up back into the 70s.

I agree with the above poster, you may have a leak. How cold does it get in South Florida at night, and do you park it outside? I drive on summer performance tires all year. Actually just put on a new set of PS4S this past Friday, but summer tires can develop cracks in the compound if they get too cold. Not really an issue here, because at least for the Michelin tires that isn't a risk until temps drop into the 20s and you don't let the tires warm up first before driving on them.