I have the JLURD diesel with 315x12.5 cooper sst pro and the engine dosen't even notice the bigger tires. Stock gears and stock suspension. The only time I drop into 7th gear is on steeper highway grades. Most inclines I stay in 8th. Off road the diesel just idles over obstacles. I am thinking about getting the MC 3.5 GC lift, but not in any hurry.I am on 35/12.5/17 NITTO M/T with stock Rubicon wheels and I never hit 8th gear.
Let see on 37s