Just from my years of experience, I'v tended to inflate about 3 lbs. over what the vehicle mfgr recommends on the door sticker. I have found that to give me adequate traction and relatively even tire wear.

Interestingly, my youngest boy took a job with one of the major tire retailers. In discussing tire pressures, I told him my thoughts and he said that was exactly what they do at the tire store.

AM.

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E70 2010 3.0 M57 AT Titanium Silver with Black Leather
E53 2004 3.0 M54 AT Toledo Blue with Gray Leather
E83 2008 3.0 N52 AT Silver Gray Metallic with Black Vinyl
E46 1999 2.8 M52TU 5MT Black with Tan Leather 250K+ miles (Sold, but not forgotten)