Tire Pressure Indicator Warning Light Problem

[macmaster05]

Hey guys,

Tonight my TPMS light stayed on after the car was sitting out in the cold (41 degrees) for the first time. I just checked my tire pressures and they were 35 (fronts) and 25 (rears) whereas they were 42/40 psi in the summer. I'm at a loss - is this is cold weather issue or are my tires actually punctured?

I've had both cases and historically the light would turn off after driving (I'm guessing friction would heat up the tire/air), but it didn't turn off this time. But when there was a nail in my tire the next time, it was at 18 psi. That's why I'm confused...25 psi seems too low for a cold weather false alarm but too high for an actual leak. Any suggestions?

[Rebound]

I drove a rental car today (non-Prius; they wanted $20/day extra for a Prius). The TPMS sensor lit up for the first few miles. I mentioned it when I dropped off the car, and they told me with today's freezing temperature, the same thing happened on eight other cars today.

[wick1ert]

Originally Posted by macmaster05

Hey guys,

Tonight my TPMS light stayed on after the car was sitting out in the cold (41 degrees) for the first time. I just checked my tire pressures and they were 35 (fronts) and 25 (rears) whereas they were 42/40 psi in the summer. I'm at a loss - is this is cold weather issue or are my tires actually punctured?

I've had both cases and historically the light would turn off after driving (I'm guessing friction would heat up the tire/air), but it didn't turn off this time. But when there was a nail in my tire the next time, it was at 18 psi. That's why I'm confused...25 psi seems too low for a cold weather false alarm but too high for an actual leak. Any suggestions?

It's possible it's a slow leak. It's also possible that you happened to check it not too long after it started, too. I'd recommend filling the rear tires up to where you want them, then monitor it the next few days to see if there is any change. Given the rule of thumb, that a 10 degree temperature drop is roughly a 1 PSI drop, you needed about a 150 degree temperature change if that were the only factor. I don't think it's even quite that warm where you are.

It could be the seal, valve stem, etc that's got a slow leak, too.

I'd fill em up and do a quick check every morning to see where they are at. That'll tell you if you need to get them checked out.