I'm sure this is not your problem, but since we're on the subject...The toughest tire I ever dealt with turned out to be a problem where the tire liner ("Mr Toughie") got old and bits of innertube hardened and stuck to it and were sharp enough to punch holes in the new tubes. I stopped using the liners after that and I always change my tube whenever I change my tire. Super unusual problem but of course it started when I was 100 miles from home in Mt Pinos. Most likely culprit is thorn or rim tape missing. Another tip is to use a good floor pump. I used to use one of the little frame pumps and was constantly abusing the presta valves. They are very fragile, so be careful not to bend the little screw-in stem even when using a floor pump.