Tire pressure is very subjective. For best tire wear you need to inflate them to where the tread wears evenly across 3/4 of the tire. Off road we run lower for comfort and the lower tire has a longer footprint for traction.
If this sounds vague it is. All of this is based not on pressure but what the tire is rated at in weight and what your vehicle weight is as well as what makes you happy. When I run an aftermarket tire, I start with the pressure the vehicle manufacture wants. This is found on a sticker normally on the driver door or door jamb.
From here there are several ways to gauge if you need to go up or down. The goal is to wear most of the way across the tread, different tread designs will vary.
1. Drive it and check when you rotate. this takes the longest.
2. Drive over dirt and a short trip on pavement. The tire will rub off the dust and you will see your footprint.
3. Buy some children's sidewalk chalk, the the big colored sticks that they can draw on concrete with. Cover as much of the tread area around the tire, one front and one rear. Drive straight a short distance and see what comes off.
4. There is a formula to determine the tire pressure. That gets you closer but, its still a starting point.
The problem here is, no one can really tell you what is best. If you talk to other people who have the same vehicle, same mod's, same tires, drive the same and actually know what their talking about, you will still only get an opinion and a possible starting point. They will normally be the closest.
My TJ had tires with a 3600# capacity @ 65# psi each. That's 14400# of support @ 65 psi on a 5000# vehicle. 30 psi gave me a good ride and good tire wear.
My Cruiser has 2600# tires @ 45 psi. Vehicle weight is 6k. 38psi works best there.
Both vehicles had a 35 psi door sticker and that's where I started.
