I own an LJ with hardtop, heavy bumpers and a winch.
The Tire and Rim Association load index tables referenced in post #28 by
@AMS417 will give you an accurate tire pressure for your tires based on the weight of your rig with just a bit of extrapolation. You can use the published curb weight divided by four, but your rig will weigh more than the published numbers due to your modifications from stock. Better to stop by a public scale and get accurate axle weights.
In the meantime, to help give you a starting point, my 2006 LJ Rubicon with hardtop has a listed curb weight of 4,012#. However the real world weights are:
4,880# with driver, full tank of fuel, but empty of all gear except the factory jack and owners manual (2180#F/2700#R);
5,340# when filled with gear, food and water, driver and passenger, full fuel tank, full jerry cans, etc. and ready for a 10-day trip (2180#F/3160#R).
Calculated weight of modifications - 683 lbs. (4695 - 4012)
Approximate weight of gear, spares, tools, extra fuel and water, food, ice, etc. when fully loaded - 460 lbs. (5340-4880)
See this post for weight particulars:
https://wranglertjforum.com/threads/what-does-your-jeep-wrangler-tj-weigh.24254/page-2#post-397463
Through a combination of using the TRA load inflation tables and practical experience with this particular jeep, I have found that for my LT315/75R16 Mickey Thompson Baja ATZ P3 tires on my LJ
26 psi works well around town and
28 psi works well for long Interstate runs when fully loaded with gear.
I tried a combination of 26 front / 28 rear when fully loaded to more accurately reflect the weight differential when fully loaded but couldn't feel a difference so I decided to keep front/rear pressures the same for simpilicity.
How the jeep looks fully loaded with the tires at street pressure:
View attachment 207188