Your best bet for figuring the correct gear ratio for tire upgrades is to go out on the highway before you change tires and record the MPH at 2500, 2800, and 3000 RPM.
Take those figures and then go to Jeep Ratio Calculators
Apply those figures to that chart and pick the one that makes the most sense to you as far as the ratio that will give you the best mileage, closest to the factory, and the most power.
I went with the 4:88s in my Rubicon with 33"s and the mileage sucks. (13mpg) I may upgrade to a 34" or 35" tire though to see what change that will make.
Hope that helps.