Specialized All Conditions Pro continue to prove to be tremendously durable for a rear tire on a fixed. I just picked up a narrow-ass Tufo tubular clincher for the front end of my ride because of tire clearance issues, but I have been very happy running two of 'em for a while now. Superior grip and longer wear than any other tire I've ridden. Very good flat protection too. $40 ea, which is a little more expensive, but still very reasonable for this tire I think.