I bought my 05 about 2 months ago. Since then we have had 2 cold nights including last night which when I got in the car it was 40 degrees. This morning driving to work I noticed the low pressure light on in the dash board came on. This happened last time and the one tire was a little low. I filled the tire and it's been fine for 3 weeks until this morning again. Is this normal or do I have a small leak in the tire? I don't want to stop and put air in the tires every morning when it gets cold. Good thing I only drive my Mazda RX8 until the end of November or first snow then the Explorer Sports Trac comes out...

 

Yeah, you might have a leak. Although its common for me to get the tpms alert when the tires are cold, but when they get up to temp, they are at 32psi. I keep an eye on it, but dont worry about it.

 

I had a similar problem. After one of the first cool (40
or so) nights of the year one of my tires was down to 15lbs or so. I filled it up and went straight to the local tire place to have them find and patch the obvious leak. Oddly, no one could find a leak. So I'm keeping my eye on it. Haven't had a problem since.

By the way, RIWWP, if you're at 32lbs when warmed up, aren't you a few pounds low? I'd expect warm pressure to be somewhere nearer 35lbs.

 

Actually I usually run at 32 for daily driving. I trigger TPMS with 27 or 28psi for autocross Specific tire pressures don't bother me much, and frequently leave the pressures really low after autocross just for the feel, even though I know I'm using more gas and wearing the tires faster doing it. Between that and not having any TPMS on my winter set a third of the year, I largely ignore the light. I check the actual pressures frequently anyway.


But, I was just making the point that from 35-40 ambient to warmed up, probably 80+, you can swing a good 4 psi easy, probably more.