October 20, 2014
Proper Tire Pressure
You have to balance ride quality and tread wear. By closely observing tread wear you should be able to arrive at the optimum pressure. Wear on both outside edges, too low. Wear in the center, too high. Unless constantly operated at maximum gross weight rating typically the rear tires on a set of duals could be operated at a lower pressure that the single fronts as the weight is divided up between the four tires. As I’m sure you know the pressures molded into the tire side wall is the pressure at which the tire can support the rated weight displayed next to it.
For example this tire can safely carry 3520 pounds when inflated to 85psi when cold AS LONG AS the combined weight doesn’t exceed the max rating of the vehicle. Now, if the above truck were for towing your 16ft ski boat one or two weekends a month and just driving to and from work daily you could get by with far less pressure, probably 35 or so front and rear. When your neighbor corners you into hauling his demolished concrete patio to the dump you’d definitely air up to the 60 / 70 pressures as recommended!!
When in doubt, always err on the side of overinflating (less heat). Steering is crisper due to slightly stiffer sidewalls; cornering and braking may not be as stable, and the tires will wear faster. But overall, overinflated tires are safer than underinflated ones.
For more on the subject visit: http://www.fourwheeler.com/how-to/wheels-tires/1407-understanding-tire-load-ratings/