So your tires are E rated 10 ply I would assume. A lot depends on your travel weight, but most of the time it has to do with tire construction and intended speed.
The load capacity of your tires is based not just on total weight capacity, but also temperature. More sidewall deflection means more heat. Under inflating 10 ply road tires close to full gvw at highway speeds can significantly shorten their life and increase the risk for failure.
At low speeds, theres generally less concern as friction increases with speed. Many off road AT/MT tires are designed with lower inflation in mind. The tread compounds an construction are more suited to this deflection than gneral over the road highway tires which are designed for vertical load carrying and lateral stability at speed.
First step would be to calculate your total weight and find the pressure rating for that tire at that load. This will give you the best tread wear on paved surfaces. Then adjust your pressures down visually for off pavement. The goal would be for full tread contact. You can see your sidewall corners start to wrap down towards the ground. It's got to be pliable enough to contour to the uneven ground, but not soft enough to risk unseating a bead in off kilter situations. The closer you are to gvw, the better to stay on the cautious side of 30 psi. unless you've got beadlocks.
