I have RhinoDillo Liners in my tires cause I was getting flats daily due to goatheads, I now have not had one flat in the last 700 miles.

If you have a tire liner try this test with a tooth pick as shown in this video approx at time 1:50 http://www.youtube.com/watch?feature...&v=e9vLa32mOhk

, I did and the tooth pick does break, I also tried this test with a self tapping screw it does go through but is very very hard to do so.