My car sat for about the last week or so while I was home on spring break (I flew instead of driving the 700 miles). When I came back it appeared that my front tires had lost air. Is this common when a car sits or should I be concerned about the tires? (which were checked out as good when I had them rotated and the wheels balanced two weeks ago).

You probably have corrosion on the rim whcih is causing the small leak.

I had the same problem not long ago. Turns out the some of the chrome inside the wheel where the edge of the tire sits (bead, seal) was flaking away, creating an improper seal and allowing air to slowly leak. They brought the wheel inside and showed me. They were going to attempt to clean up the area thoroughly and re-mount the tire and hope the seal would hold, but I simply requested that they swap the wheel from my full-size spare out with the one there instead.

Though that's just one way a tire can lose air. For me I knew it had to be something like that because there was no visual puncture and it took forever to lose the air. I'd take it somewhere and make certain that there are no punctures, and then have them test for slow leaks. Just explain what's going on.

maybe someone let your air out.

check your valve stems- they might be corroded.

spray your tires with tire shine and try to figure out where the leak is.

if you have a discount tire co. over there i know for a fact that they fix flats for free.

Has it gotten colder since you left?

Yeah the weather has been all over the place. It's not like the tires are flat either, they just appear a little low (I haven't confirmed this yet with a tire pressure gauge, just by eyeball).

Fill em' up and take some readings over the next couple of weeks.

It's probably nothing.

Yeah that's the plan. The local tire place said they'll do a leak test for free so I'll have them do that and then go from there.