bombproof for crosscountry riding. I love them. I have a 2 wheelsets built up with them and am about to build up a 3rd set. They are so tough that I bottomed a tire a few weeks ago on Gatorback, too low of air pressure and caught a paver that was supposed to be reinforcing a hill but had got knocked down about 1ft from the other, I caught the edge of it hard. It bottomed on the rim hard enough to puncture the tire, which is a first for me. Never dented the rim, bent or nothing. Only thing you can see is it took a very small chip out of the paint on the rim.