Ok, I'm going to jump in with one more point just because we should make this topic as complex and confusing as possible!

Running close to max on a mt bike can be good and bad. Good for preventing pinch flats, bad for losing traction. If you are running a full suspension bike you can run lower PSI. Lower PSI can make the tires bite into the trail better. Higher PSI can make you bounce off the obstacles. Plus, you have to factor in your weight. That same good feeling of low rolling resistance on a road bike isn't necessarily so good on a mtb. You kind of have to play around with PSI till you find an optimum range and then adjust for trail conditions. I also don't pump up my tires until I reach my destination. Here in Calif I live at 25 feet above sea level but with a 2 hour drive be over 7,000 ft.