On a recent ride to France 4 miles in and my back tyre exploded, a friend who i was riding with at the time gave me a spare tyre (the GP 4000), i rode 400 miles with this tyre, had no problems with it and improved the ride quailty some what. On comming home i bought myself another for the front,they have seemed to increase my coasting speed and have much better grip compared to my previous tyres. (Schalbe Luganos). I have since rode a further 600miles with these tyres and are showing little wear. Overall im very happy with them.