My tc for some reason keeps losing air pressure in the tires. Not sure why but this morning one of my tires was down to 20 psi. They were 30, 28,27,20. This is the third time.. I have to wait til later to take them into the shop.

maybe one of your friends is playing a joke on you? or someones hating on your ride. ive had that happen to my once. my stupid next door neighbors were mad at me. so they decided to deflate my tires. so i aired them up and ever since then my cars be in my garage and tires never gone flat.

if u dont think someone is messing with u...take it to the dealer and get it fixed via warranty

if u think someone is messing with u...get valve cap locks

It's probably just a bad valve stem. It happens. Take it to the dealer and have them replace it. Even if they charge you, it shouldn't be more than $25 to unmount and remount. Simple fix.

If it's not covered under warranty, you'll probably want to go someplace other than the dealer. Dealer will be quite a bit more than say Walmart and as Jon said, it's a simple fix.

After my 5k service, literally 10 miles down the road my front right tire went flat. Loose valve stem and a nail from the construction at my dealer.
Anyways, fill that puppy up with air and spray soapy water all over it. You'll find the leak, may be more than one leak. Don't stop checking after finding just one leak, check the whole tire and valve stem. Myy local shop missed the nail on first inspection, I was not happy pulling the same tire off twice.

After my 5k service, literally 10 miles down the road my front right tire went flat. Loose valve stem and a nail from the construction at my dealer.
Anyways, fill that puppy up with air and spray soapy water all over it. You'll find the leak, may be more than one leak. Don't stop checking after finding just one leak, check the whole tire and valve stem. Myy local shop missed the nail on first inspection, I was not happy pulling the same tire off twice.

nail from construction at the dealership during service?

please tell me you went back there and had them replace the tire? Toyos are some damn expensive tires (which makes it great they come standard on our tC2s) and if it was their fault they should give you new ones at no cost

i got a bump on my sidewall (my own fault) but i talked to my service guy about it and originally said i would pay half for a new tire and they would pay the other half (the tire was like $235 for 1 or something)...but they were so cool that they decided to cover the whole tire...i just needed to pay the $20 labor

so if u got a nail flat because of them...i'm sure you have every right to have them give you a new (expensive) tires

Yea I don't know why I'm worrying so much because I have road hazard warranty for my tires which actually does cover the tires If I was to screw them up which I have before lol. But it's just weird that all four of my tires are doing the same
Thing

Road hazard warranty is nice. I had a nail in the inner sidewall of my tire. No idea how I pulled that one off, but they covered it no problem.

A local shop that gives me a company discount repaired the tire. They repaired the tire in front of me correctly, not hiding in the back of the garage like the dealers.They also are 1.5 miles from my house, the dealership is 15 miles of heavy traffic. It would have been more of a headache than I care to deal with to get the dealer to fix the tire. The nail was in the rain groove of the tire's tread, so no major damage. Tire is holding up fine, no leak. My Scion/Toyota service dept. looks like a McDonald's drive thru at lunch hour 24/7. I doubt I will ever return there again unless necessary.

I don't know if you have a Firestone shop around your area. If yes, I would recommend take your car there to sort out the problem. My GX470 was losing about 10 psi over the night. Firestone got it fixed on less than half an hour. They found a huge 2 inches nail in the tire. And the best part is, for some reason, they fix the tire for free.

Yep. Firestone does it the right way. Internal patch with a stem thru the hole in tire, glued in with the same glue used in our tire building process. Never repair a tire's sidewall or buy a tire that has been repaired in the sidewall area. Exetremely dangerous and illegal in most states. Always get road hazard on tires. It pays for itself every time, at least for me it has.

For those that are talking about nails in thier tires being a possible cause for this. Mike is saying that all 4 of his tires are losing crazy amounts of air...

Just some FYI for you guys on tire repair:

http://en.allexperts.com/q/Tires-2359/2009/4/Loss-Warranty-Speed-Rating.htm

This is not the first time I have seen this discussion about repairs hurting speed ratings, and IMO, it makes sense. Your tire is only as strong as the weakest point.

Andrew, what was the diagnosis?

oddly enough, a week ago my light came on, and all 4 tires were right about 20. first time since i bought the car in march. filled em back up, and seems to be alright. im *thinking* my problem was im from texas, and was visiting colorado and the colder temp/elevation caused it, but not sure