Another thing to consider- when did you pump air into your tire? If you did it just before your ride, maybe the tube was bunched in one part and it finally did blow after 12 miles of riding.

Also, you may want to consider slightly inflating the tire and holding it underwater to see exactly where the hole is. It could be just that the hole is too small to detect otherwise.

Consider taking a wet sponge and wiping out the inside of your tire- there could be a tiny bit of debris inside the tire that you can't feel, but if you just rub the sponge a few times on the inside of the tire, you may be able to wipe out the offending debris.


Koffee