I use kevlar belted tires as well as tire liners with slime tubes. Ain't much you can do about big honkin nails or screws, but if you live in an area with big thorns/goat heads (I'm in Albuquerque), then the slimes are your best friend. Even with heavy duty tires and liners an occasional thorn will get through. And I would suspect it would get through a thorn resistant tube as well. With a good slime tube, it's not a problem. Otherwise you get a flat. It's a nice last line of defense, as eventually a goat head will puncture through even the toughest defenses.