Since we're talking flats here, I had the fortune of 2 flats on 2 different bikes this week. One on the front tire (: and the other on the rear. Turns out the leaks on BOTH tires were on the edge or seam where the tire is joined. I hadn't changed either of these tires in a couple of years, so no surprise that the tubes finally gave out.

I recommend that you keep track of when you put your new tubes in your tires (or mended ones) so you don't have to go through fixing flats on the road like I did. I have 2 more tubes to change out as they too are old. The tires on both bikes are fine so it wasn't about a bad tire in either case.

Also, someone has probably mentioned this before- I'll say it again. If your tire shape begins to look flat on the top, you might consider changing it out for a new tire (tires start out round and flatten as they get miles on them). I say this because you do lose some of your handling ability especially when going around corners at a good clip. I really noticed a difference in the handling of my bike after I put a new tire on the rear.