Higher pressures?
Tire pressure is adjustable for ride, handling and wear. You don't inflate the tires to the max listed on the sidewall. Good practice is to inflate to what the vehicle manufacturer recommends in the manual or on the door sticker. Best practice would be to calculate it. The sidewall of the tire gives a max pressure for the max load rating of the tire. Divide those 2 numbers and you get a recommended pressure per pound of load on the tire. If your truck weighs 3600 lbs, divide that by 4 and you get 900 lbs per tire, for example. Then multiply that by the psi per pound that you calculated from the sidewall. Now you know how many psi should be in that tire. You can adjust that as needed. An empty truck may have more weight on the front and less on the rear. So, maybe try a 60/ 40 bias with the higher pressure in the front tires. You may find that these numbers come pretty close to what the vehicle manufacturer recommends. You can also check the contact patch of the tires and adjust pressures to get the amount of contact you need or want. Offroad, lower all the pressures to get smoother ride and bigger contact patch so you don't sink into soft ground as far or to help the tires grip rocks better.