How about a less expensive, name brand, non-puncture proof with a tire liner like Mr. Tuffy? Mr. Tuffy's last forever and you simply transfer from tire to tire as they wear out. I think it's a good investment. I've been using them for the last 15,000 miles and have only had one flat (knock on wood). It was caused by the Mr. Tuffy itself. It was in there so long it actually wore a hole in the tube. So it's a good idea to rotate where the tube contacts the overlap of the Tuffy every so often. Others recommend talcum power on the tube to prevent this problem.