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[ajminn]

The other night, I parked the M3 outside instead of in my garage. The temps have been getting a little bit lower at night, but nothing crazy (I think the low was around 44F). That morning, I start the car and get low tire warnings on all four tires. I thought, okay, normal just because it was cold; the error should reset by the afternoon when the temps had risen into the low 70s, and the air inside the tires had heated up. That afternoon, I still had the warning on all 4 tires. Parked the car in the garage last night, and still had the same error again this morning.

Haven't checked the pressure yet (which I know I should have done and will do this afternoon). The tires obviously aren't flatted. I thought I had inflated them properly during the summer, but now I can't remember. Does the psi inside the tires change that drastically from summer/winter? Anyone else experience anything like this? I'm assuming it's just low tire pressures and isn't a real electrical gremlin or anything, but I thought that the afternoon sun would have heated the tires back up to the optimum pressure. Thoughts?

[konaforever]

I've read that the tire PSI changes 1 PSI for every 10 degrees F.

[kscarrol]

You're right, the cool weather can cause pressure to drop but it should have moved back up as the tires warmed up from driving. Over time, tires will very slowly lose some pressure so the only way to know is to actually check the pressure. If the pressure is normal then you have some malfunction is the TPMS. Could also be a case of the tires are simply low and need to be topped up...

[Rshane]

TPMS will not reset itself, so even if you add air to bring the pressure back up to optimal levels you will still need to manually reset the TPMS sensors via iDrive if you have it...not sure how without iDrive...computer I suppose.

[Mr. ///M3 RD]

You need to actually check your tire pressure (as you are planning to do) then if they are within spec reset your TPM

[Foodle]

Same thing happened to me a couple of weeks ago when there was a cold snap here. Manually checked tire pressures (all ok), then reset TPMS. No issues.

[TVMA Doc]

Originally Posted by konaforever

I've read that the tire PSI changes 1 PSI for every 10 degrees F.

It also changes quite drastically after being left outside with unattended valve stems. I'd make sure that it isn't some neighbor letting air out of the tires. Then, do a reset on the TPMS.