I seem to be averaging the same number of flats per year regardless of width of tire and pressure, and the 25mm tires that I buy have extra kevlar reinforcement which may possibly even things out. Oh, there's one factor about running 25's that I didn't have with the 35's, it is the fact that the 25's pinch shoot small pebbles/rocks out to the side of the bike. Most of the time, the pebbles/rocks only go a couple of feet, but there are time when I can set one off as though it was shot out of a slingshot, and they have nailed some shiny new vehicles that were parked across the road with some seriously audible force. I'm not so much dreading the day when I tag someone's vehicle while they're washing/polishing it and they chase me down, but I'm more worried about hitting a ped walking on the sidewalk, I came close a couple times.