I've not had good results with Slime. Tuffy liners certainly have helped. The only real solution, I think, is stronger tires -- slime and Mr. Tuffy are just "band aids" that fail to address the root cause, which is tires optimized for recreation, rather than utility. I've not had a single flat in 2,800 miles on Schwalbe Marathon Plus. I've also heard good things of Conti Top Touring and Specialized Armadillo.

Paul