I did run 33x10:50 on my stock Rubi LJ for a short while...............no way could you off road it....also a little rubbing on some bumps.
31's will fit fine .......may get by with 32's
White 2005 LJ, Rubicon, Rubicon Express 3.5 SuperFlex, Goodyear 315/75/16 MTR's, Pro Comp 97 16x8 wheels, UCF Tummy Tuck, 1" Prothane BL, 1" JKS MML,Tereflex Disco's, 10,000 lb. winch. CB Radio, Fire Extinguister, Synthetic Fluids, Driving Lights....
1999 XJ 6.5 Lift, Rusty's Long Arm, Four Link Rear Suspension, ARB Lockers Front and Rear, Alloy Axles....