Does anyone know for sure what the max. PSI rating of rubber valve stems are? The shops that do our work truck tires (1 tons with load range D or E tires) always use metal stems stating that rubber can't handle the PSI of D and E range (65 to 80 PSI). 4WPW says different and puts rubber on D and Es saying they work fine. Well, guess what happened?? Any info. from those in the tire or wheel business would be greatly appreciated before I start making a stink with my Buds at 4WPW. Thanks, Eric M.