when installing my Schwalbe Marathon Plus 700x25 tires i pinched two tubes spending 20 minutes wrestling to get the final edge of one tire on with plastic levers.

Someone here recommended using a some liquid dish soap to lubricate the final edge of the tire/tube/rim. (You can also buy special lube for this). Once I tried dish soap I had the tire on in 3 minutes. No more ruined tubes and not one flat since.