I just had an issue with a low-mileage Kenda 28-622. The Kenda's are stock from my 2010 Fuji Absolute.

Absolutely no abuse: I don't ride hard, city only, on well paved roads, always with full inflation. Maybe 300 total miles on the bike. Cheap stock tires and 10 years of aging rubber, methinks.

A small tear (1mm x 10mm) on the rear tire's wear-tread led to a flat just a few days ago. I got off lucky -- the tube burst like a balloon just as I was wheeling it back inside after a 5-mile ride.

After patching the tube, I cut a piece of thick patch cloth for the inside (the iron-on type, but I just used Scotch tape to affix it -- I might rubber cement later if I have issue). As far as the outside, with the tire deflated, I inserted a bit JB Weld into the tear and surrounding area. Just enough to seal and cover the surrounding area. I'll see how all this holds.

BTW: Any thoughts on replacement tires for the mostly-city-use hybrid bike? Are Kenda's okay? I've had good experience with Conti's. My $ range is max $25/each.