31x10.50's is really cutting it close, how heavy is your wife and mother-in-law, that could be the deciding factor... 31x9.50's, no problem just dont hit any sudden bumps while returning from the hardware store with a few bags of sand or cement back there... and shim the steering stops on back side of the wheels, looks like a bolt that does not do anything, back it out and build it backup with some washers...3 or 4 should do it..
LT235's and 30x9.50's will work well, just don't disconnect the front sway bar when off roading, that extra 1/2" from 235 to 30 makes a difference, I can disconnect with 235's but not 30's...not unless they are really really really worn down...