3000 miles on my last set of Conti Grand Prix (not the GP 4000sII) and they still had life in them, never flatted or blewout or sidewall damage. I bought the GP 4000sII 25MM for a vacation to the mountains, 2nd day on the 2nd climb I blew out the rear from sidewall tear. I replaced tube, booted tire and made it up over the climb, skipped the 3rd climb, stopped at a bike shop to replace the tire and then continued to the 4th climb. That tire had something like 60 miles on it before it tore so it's not mileage, it's wear and road conditions etc. BTW this was first set of 25s and I love the ride. Next time I think I'll order the regular GP in a 25mm if I can't find it locally, I kind like it better than the 4000sII so far