My rear wheel went flat. I examined it, screwed down the valve, pumped it up and it held air better...But just to be sure I had a guy at my LBS look at it. He put in a new tube.
I got it back and it was fine...but next morning it was flat again...

I was just about to go on a ride...so I filled it just to see. I fiddled with the valve and the tire was great for all 22 miles.

This morning..I think it lost a little air. I wonder if it could be that the cap has a defect that is pressing on the valve???

Any ideas?