Tires are all different, JK weight different, etc. Too many variables. Solution: find a straight, open road and do a chalk test: chalk up tread, drive a bit, observe chalk wear. Takes time, but it's the only way to find out the proper pressure for your rig.
Wear in the middle: pressure too high.
Wear on edges, pressure too low.
Wear even across tread face: pressure just right.
If you don't have time to do that, you can air your tires and look at the contact on the road while you're doing it. Same principle, just not "dynamic" - so you'll have to check a few times after you go out for a run. Generally, big tires need less than factory tire pressure, around 28 psi would be a good starting point. Wide tread tires have a tendancy to balloon out in the middle of the tread at higher pressures, and cause uneven tread wear in the center.