after 9 flats in a 3 week period , and that is AFTER replacing the first tire which flatted the initial 4 times, (5 more flats on next THREE rides!) I finally put a DuraSkin on the back wheel... not as fast as a race tire, but the time I save not stopped changing a flat has made it worth it! I commute too and (knock on wood) have yet to flat on this tire... and have ridden 2 century's on them in the last 2 months too!