Check what's teh max pressure rating for the tire and you're safe in any pressure setting below it. You can safely go to 35psi IMO (we do that with our cars sometimes).
Try experimenting with the variuos psi set-ups until you get what you feel is the best compromise between performance and comfort. On our cars, i usually run 31-33psi (not much tire squeal during cornering and better road feel).
Running on a higher psi rating for your 45series tires will also help protect your rims from damagae or "bingkong" a little more and also improve your fuel mileage a bit.