Just bought an 04 Rubicon (100% stock)and am looking to to make some upgrads.  I live in CA and will be doing moderate off roading.  The Jeep mechanic says I shouldn't change the wheel size because it affects the brakes and balance.  What do you guys think?  What is a good wheel and tire size for a stock Rubicon (will lift as needed)for moderate off roading yet, maximizing street milage?   Seeking the balance between offroad (10%) and the street (90%)...  

i did a 2" budget boost for $250 and 31x10.50 bfg mts and it goes pretty good with the stock 4.10s, i swapped in 04 rubi front and rear ends. rides good on the street, and i didn't notice much if any mpg change. it was the first thing i did to my tj and don't regret it at all, though i am planning on going with more lift and tires soon! it is a good cheap place to start, though i wish i would have done a 1" body at the same time and went with 32x11.50s being as it wouldn't have cost much more and would've got a little more floatation and a touch more clearance. as for the brakes, the four disc brakes that are on your rubi will work fine. you are probably not going to stick anything bigger than 35s on the end of the d44s anyway.