I recently got into biking, ride about 1,000 miles per season (roughly Mar - Nov, I'm a fair weather rider). My first season, I had 6 flats. In desperation, I bought tire liners, got a flat with those when the edge wore through the innertube. Melted the edges of the liners smooth with a cigarette lighter, have now gone about 1,500 miles without a flat. Just throwing out the tire liner option as an idea. I have Mr. Tuffy on one bike, and Stopflats on the other, they both work well.