Normal tire pressure

I would narrow the range a bit and guess that 28-32 psi would be the sweet spot for that size tire on the highway.

Every jeep will be a bit different - pick a pressure somewhere in the middle of the range and experiment up and down.
 
If you are getting good wear with no oddball patterns or cupping then you are in the right zone. A bit less psi will help to soften the ride. A bit more may help it roll easier.