On my Kona, I have Mr. Tuffy liners, have not had a flat yet. My LBS never seems to recommend tire liners, they seem to frown on them - please someone tell me why - they move around, etc. - I don't know. My Giant road bike I had a flat on recently, I was told I had about a month of life left on the tires, so I changed them for Continental Grand Prix. So happy!