I have a 2012 unlimited on the way. My original thought was to switch my Sahara wheels with 35" trail grapplers with the stock rubi wheels and tires. But now I'm wondering if keeping the rubi wheels and buying new tires for them might be a better choice. I here some say that tires on the 18" wheels do not perform as well as they would on the smaller wheel. When I say this I mean with the same size tire on each wheel.
But then I might be tempted to go with 37"s if I bought new tires.

 

Here is mine. 35" trail grapplers on stock 18's. Honestly not much difference in performance between 17's and 18's besides they are more expensive