Originally Posted by KLiNCK

Your rim tape may need to be replaced. I was recently working on a bike that needed to have a spoke replaced. I had to remove the rim tape to change out the spoke and true the rim. Rim trued no problem, and I reinstalled the rim tape, tube and tire. Every time (7x !!) I tried to inflate the tube it would hold air for about 5 minutes and then would go flat. I originally thought that perhaps there was "sharp" somewhere in the tire that was the culprit. Checked and double-checked (and triple-checked), couldn't find anything. I did notice, however, that the tube was being punctured at a different spot each time on the side that seats against the spoke holes of the rim. The original rim tape seemed to be fine and was still covering the spoke holes every (7 LOL!) times that I checked/patched the tube. This was a 35C tire and I was able to mount it with out tire irons so it wasn't pinch flats. WTF? I put on new rim tape (and a tube) and everything was fine after that. I guess the old rim tape was "creeping" when the tube was being inflated and exposing the spoke ends which would then puncture the tube but then slide back into place as the tube lost air ...
I had never run into that problem before!