tire/rim help

I am getting a set of 31x12.50x15 boggers here soon and i got thinking about rims. I still have the stock 15x7 on my 31x10.50 tsl's. Will the stock rims work or should i look for a set of wider rims with a different backspacing. These will be going on a 91 xj which is going to have a 4.5" lift and trimmed fenders.

Thanks,
Ben

get new wheels, 15x8's with less then stock backspacing, 3.5-4.5 inches

I second the new rims, with the 31's on stockers you don't have a whole lot of room to clear suspension goods, etc. Adding 2" of tire width and I don't even think they would turn freely. Less BS for sure.