Any thoughts as to why BMW recommends fully loaded pressures all the time on BMW 528i's (1996-2000) driven in the US and Canada -- i.e., 33 front, 41 rear, while recommending 29/33 for partially loaded (up to 4 people) outside the US. I tried the 33/41 pressures driving the car alone, as I usually do, and found the ride to be terrible. Also, is there a "best" tire gauge? Are the digital ones better?