My Conti GP 4 Seasons tires have 3,300 miles on them. A couple weeks ago I noticed this small spot on the rear tire where the outer layer of rubber had come off. It was holding 100 psi fine and I rode it home from work yesterday 15+ miles.

Today I got home from work and found the rear tire completely flat. I found a tiny tiny leak in the tube, but I'm pretty sure it wasn't in the exact spot as this spot on the outside of the tire. I put a patch on the tube and got it all back together and aired up, but I'm not too sure about this. I went ahead and put my old stock Vittoria Zaffiro 700x25c back on for now. Should I not use this GP tire at all anymore?