I run 31x10.5 Michelins on the stock aluminium wheels on mine. When I first got them they would rub on the plastic inner wheel well in fron on tight turns (usually backing up). As long as your shocks are good and you aren't going with wide wheels you should be okay. The speedo on mine reads about 10% low (if it says 55, I am doing 61). Changing out the gear would have been easy, but I only plan on driving it another 100k miles or so.
If you have the 3.27 gears, you will be sorry if you go with bigger tires. My 3.73's are just bearable with these tires. It has gotten better with the new breather stuff...