I switched to the Conti 4000 tires about 400 miles ago because of excessive puncture flats on my other tires. They have been great, until the end of last week when I got a sidewall split on the rear tire. I don't know of any road hazard that would have caused the split, so I chalk it up to a weak area in the tire. I have ordered another pair of the 4000 tires from PBK and am hoping that the sidewall issue was a fluke.