A 31x10.5 Super Swamper TSL SX would probably be a better tire for you. Boggers are
so heavy, and they hook up so much in the mud that you'd better have V-8 power to spin them. Do you have V-8 power? Fill in your profile so people can take things like this into account when they give you advice.
Now, onto running 31s on a stock Jeep. If you keep your stock rims, you wont rub the hell out of your fenders with the steering wheel straight. The tires will tuck right up inside the fender-well. If you disconect your sway bar and both trac bars (which you dont
need to do if all your running in is sand and mud...) you will be able to contact the metal lip of the fender and eventually (with a thorough thrashing of the Jeep) bend it up some.
To clear 31s without a chance of them hitting, a 2.5" suspension lift is best. But lets face it, a 4" lift costs the same, so what are you going to get, right? /wwwthreads_images/icons/laugh.gif
To "cheaply" clear the 31s, I'd go with 1/2" lift shackles and a 1-2" body lift.
To
really cheaply clear the 31s, just use a sawzall /wwwthreads_images/icons/crazy.gif