How much tire damage is too much? This Continental Contact had roughly 1200 miles on it before an arrow-shaped rock about the size of a BB managed to plant itself right under the valve stem and mess up my ride home today. I pulled it out, replaced the tube and it ran just fine going home. On the outside it looks like about a 3/16" cut while on the inside it's no larger a hole than any other goathead would produce, but it's a fairly deep slice. I was hoping for at least 5,000 miles out of this puppy!