1) I've got a Specialized All Condition tire that picked up a piece of glass today. I plucked the glass bit and all appeared OK for about 20 miles then the tire went flat. I pulled the tube and found a pinhole in the tred side. I went back to the tire and using the tube for reference hunted for any sharp objects. I found a small nick in the outside of the tire and a pinhole in the inside. I felt inside and out carefully, pushed on the spot from the outside while feeling the inside, flexed the tire and even tried a cotton ball, but could find nothing sharp. I put in a new tube and put on another 20 miles then had another flat. I haven't fixed it yet, but I suspect that I may have missed a tiny bit of glass buried somewhere in that hole. I'll know for sure when I pull the tube and line up the leak with the spot on the tire. The question is, assuming it is a bit of glass still buried in the rubber of the tire and not just unfortunate coincidence of having two flats on the same tire within 40 miles, is there a good way to remove that/those bits when you can't feel them from the outside? Could something like a sewing needle be used to probe the hole? Any better ideas?
2) Related to first question; I now have two very slightly used tubes, one of which has already been patched. Should I keep the patched tubes as backup, or would you trust them for long term used in a tire that runs 120 psi?