Whatever pressure you use, (I prefer Volvo's pressure for a full load) you should watch your tread wear carefully. I measure mine each season.

If your tires show signs of over or under inflation, you should make the appropriate correction.

It may sound silly, but we check tire pressures weekly around here.

As another poster mentioned, the tire pressure that you run is a function of tire size, type, and the weight of your car. For instance - I purchased a set of oversized snow tires for our 745 because I plan on using them on one of our 850s after I sell the 745. Consequently, I run 2 psi lower pressure than the plate on the door calls for.
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2 8s & 2 7s 600,000 miles total