Check out this chart to give you some idea.
Jeep Wrangler Gear Ratio Guide
Keep in mind though - too high a gearing (lower numerically) can cause lugging which is not only bad for the engine, but does not necessarily increase mileage just because you RPMs are lower. I'm pretty sure that ideally you want to be somewhere in the middle for best performance/MPG compromise.
For example - my Wrangler came with 30" tires and 3.73 ratio. To get back to that factory set up with my 33s, I need 4.10s. 4.56 would give me slightly less MPG, but also a little more oomph.
Then again, what the heck do I know?