Originally Posted by
Pig_Chaser
I suspect something in your tire.
I had a situation where my front tire went flat twice in two days. Now i know how to fix a flat and I ran my fingers along the inside of the tire after the first flat and found nothing, so i fixed the flat and off i went. After the second flat in as many days, again i felt the inside of the tire and found nothing. However my suspisions told me something was wrong since it wasn't a pinch flat and the hole was on the onside of the tube where it makes contact with the tire. This time i scrutinized the tire in the location of the hole by flexing it and sure enough i found a small piece of glass that was actually imbedded in the tire.
The moral of the story: Line up your tire label with your stem so that you can scrutinize your tire in the area of the leak.
Also mark you tube with a permanent marker so that you put the tube in the same orientation when you put the tire back together. This is particularly handy for those slow leakers. If you end up with more then one patch in the same place, look for the poker
I pump my tubes up so that they are about double the size (cross section diameter) of normal and then dunk them to find the leak. If it a slow leaker, you may have to move very slowly and knock the bubbles that normally form on the tube off to see if any new ones form.