The tire will have a max pressure, but I don't think I've ever seen a "normal" pressure. It will depend on the use of the tire, and yeah, at 310lbs, you may want a little more pressure in it, but if it's a road bike with 100psi in the tires, I don't think your weight is going to matter as much as it would on say a mtb tire with only 45-50psi in it. I strictly go by feel on my mtb, meaning if it's got too much pressure in it, it will lose grip considerably, be **** on the brakes, and wash out easily in general, bounce off of obstacles, etc. If it's too low, it will be a slug to ride. Just keep in mind that whatever it says on the sidewall is the maximum to ever use period and has nothing to do with what it should be at for your specific use, just like your car tires.
Last edited by License2Ill; 07-18-13 at 06:01 PM.