Michelin prints a little chart on their packaging about tire pressure:
http://www.michelinbicycletire.com/m...rpressure.view
Since I weight about 200lbs, I fall into the "inflate to maximum pressure indicated on tire sidewall" category. For my current tires (Maxxis Fuse--came on the bike, and will be coming off before the next ride. they're well squared off after about 1500 miles, and they love the taste of glass), that's 120psi.