Why are my new tires going flat?

[who8myrice]

Oscar-
I need your help! I just recently purchased the BF Goodrich g-Force T/A KDW. I have a 2003 Quattro A4, lowered with H&R Springs and adjustable Bilstein shocks. The tire size is 235/35/19. I noticed on Saturday that my right rear tire started to go flat. I checked the PSI and it was at about 20 psi or so. I inflated that to 40psi and proceeded to check the rest of the tires and do the same. Sunday morning, I go to check my tires and they are flat again!!! I went to Costco yesterday to have them check out the rear right and they found a nail in the tire. Problem solved. They didn't find anything wrong with the rest of my tires and sent me on my merry way. I went home and let the car sit for a few hours. Drove to the nearest gas station to inflate my tires cold and retire home. This morning I check the pressure and it's near the mid twenties again! What could be causing these tires to go flat if they cannot find anything wrong with them? Any advice would greatly help!

[Oscar@tirerack]

Pehaps the patch was not done right, and also have the valve stem changed. Thats where I would start next with.

[HotSauce]

If possible, fill up a large tub...Like a bath tub, remove the wheel, and stick it in the water. You should see bubbles from wherever the leak is. I'd say go from there.

[Chard]

Maybe your rims are bent. I'm in the Bay Area too and the roads here are crap. That's an easy visual inspection. I'd bet they were bent on the inner lip if you're lowered though.

If not that, then you either have a nail in your other tires as well, or the valve stems are leaking.

Check in this order.