I just got a new set of Panaracer Col de la Vie tires for my '69 Raleigh Superbe (from Harris). The suggested inflation is 45-55 pounds. I'd like to run them at higher pressure. Does anyone have experience with these tires, and know how high a pressure they will take? I'm thinking 65 pounds couldn't hurt too much, but what about 75? Also, what should I watch for as indication that I'm at too high a pressure? Thanks!