Originally Posted by Mr. Adventure

To get to the maximum load rating of a tire, you have to go to the maximum pressure on the sidewall. So tire pressure needs to be set based on load conditions, and load conditions when towing are higher.

In the old days I got tired of the tire guy always blaming my alignment problems at replacement time because of those worn edges with better tread in the center. I found that pressures closer to the sidewall max give me better gas mileage and much better tread wear than the doorpost spec in everyday driving, and boosting the tire pressure is the only way to make tires wear evenly.

After Ford found out they had big problems with recommending 28psi tires on early 2000's Ford Explorers, I decided you can't afford to just believe everything they tell you. A side benefit is that I haven't had a tire guy complaining about my alignment in the past 20 years. I also prefer the crisper steering that comes with higher inflation pressures.