Originally Posted by Tim McKittrick
I thought at the time that I may have caused the failure by adjusting the tire pressure with the valve stem at the bottom 6 o'clock position, and that in so doing may have blown a bead into the core of the schrader valve. However, I would think that this would have caused a persistent and audible leak, and I would hope that that's the sort of thong I would notice. So now I'm not certain as to the mechanism by which the bead got up under the valve core- but I do believe that this is what lead to the tire going flat.
Do not discount chance during inflation as the mechanism. When I worked nights for QuikTrip, I once made a money drop into the safe, and it bounced just right and tripped the door open switch (normally operable only by a key possessed by the armored car company), leaving a couple of thousand dollars just sitting there in the open. I couldn't believe what happened, so I investigated the mechanism while the safe was open (and I had to yank the just-dropped envelope out of the back of the keyswitch, anyway). Turns out that the inside of the keyswitch wasn't shrouded and the contacts were exposed. I closed it up and pushed the Door button to re-lock the safe, then told my manager about the incident the next day.