45 is WAY too high for those tires.
Easiest way is to chalk test them. Run a piece of chalk across the tread (single line, side to side) and drive it a SHORT (like in feet) distance. Chalk disappearing evenly across the entire tire = good. If the chalk disappears across the outer parts only, not enough air, inner only, too much. Try it with your 45lbs, I bet you lose the middle 3rd of the chalk but not the rest.
Best PSI for those tires on that jeep (unless it's built and heavier) is about 31 PSI. Maybe a lb or so more. Less than 35 for sure.