My wife’s front passenger tire went flat a couple weeks ago while sitting in our garage. I filled it back up and monitored the pressure for a few days and it wasn’t leaking. I figured it was some freak thing and just forgot all about it until this weekend my wife left her car out in the driveway and the tire went flat over night. Filled again and it looks to be holding air.

Any ideas?

I think I’ll take it to my mechanic and have him dismount the tire and change the valve stem really have no clue.