Even tire wear is the goal. I draw chalk lines across the face of the tires and drive for a couple hundred feet, looking to see if the chalk lines are worn evenly.
If the outer edges of the lines are still visible, the tire is overinflated, if the center of the line still present, it's underinflated. I also regularly check the tire wear using a tire depth gauge.
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The ideal pressure is the result of the tire size, rim width and how much weight is on each tire, this number will change from vehicle to vehicle and from trip to trip, depending on the Jeep's cargo load.
When I ran 31"s, the pressure worked out to 30-psi in the front and 28 the rear, with a normal load. off road, they were set at 14-psi
The present 33" X 10.50s run at 28 front and 26 rear, on the street.
Off road, the pressure is dropped to 10-12-psi. This is on regular alloy rims, it could be a lot lower if running bead locks.
I ran a set of 33 X 10.50 KM2s a few summers ago, in Colorado, and found that dropping the air pressure had next to no effect, the tires were so stiff.
Dropping the pressure made the rear end very loose, tending to easily spin the rear end out when on dirt or gravel. The KM2 needed more air pressure to be drivable .
I was happy to sell them and replace with a set of KO2s. YMMV