tire issues
 

has anyone ever had a problem with tires losing air when the car is moving, yet keeps pressure while parked? first i figured i ran over a nail. then when i filled the tire to find the leak there was nothing. held air for a few days so i took the car out for a quick spin and found both back tires lost air. brand new wheel tire combo. i have under 20 miles on them. any ideas? thanks!

That's a real stumper, the only thing I can imagine that would change between runnibg and sitting would be the interface between the tire and wheel, causing it to leak by the bead seat. I know it would be a pain, but if break down the beads and reinstall them with some dishsoap in the bead area the soap (not soap and water just straight soap) this will help them seal in the bead area.