Always maintain the minimum pressure, and never exceed the Tire Manufacturers
recommended inflation pressure.
On all of the trucks I have owned, 3/4 ton and under, I have averaged 32-34
psi front, and 32-38 psi rear, depending on any load in the bed, or towing
a trailer, etc...., (for rear pressure).
Always check tire pressure cold, very best time is when the truck/trac has sat
overnight, or at least make sure your tires and wheels are cool to the touch.
Another helpful hint:
Add or subtract one pound of air pressure, on average, for every 10 degree
rise or drop in air temperature.
In other words, if you have checked your tires with an outside temp of 90
degrees, 35 psi, and the next time you check them, the outside temp is 40
degrees, your pressure will probably read 30 psi, provided there are no other
factors such as a leaking wheel or tire.
Hope this helps!