Postby SilverGhost » Tue Mar 09, 2010 2:28 pm
I'm pretty sure that the recommended pressures shown on the door sticker are based, in part, on the "load rating" of original equipment factory-installed tires. Those were/are basically highway-grade passenger tires with a load rating of 110. Both the Generals that came new on my truck, and the Michelin Cross Terrains I swapped for, are load rated 110 and have a maximum inflation pressure of 35 PSI (cold) stamped on the sidewall. Many heavier duty tires have a much higher load rating / max air pressure. For instance, the Geolander AT/S 275/65/17 that I'm considering buying have a 115 load rating and max pressure of 52PSI (cold). There's no reason not to run more than 35 PSI in a stronger tire, if that's what you want to do. Just depends on usage vs comfort vs performance. Using that type of tire, several folks on this board believe the sweet spot is 40-45 PSI. I'm unable to explain off the top of my head, though, why the tire you have is 110 load rated but can handle up to 51 PSI. Possibly either the tread, or the sidewall, (but not both) is stronger than original equipment tires.