When I got new tires Bfg ko2 32X11.5X15, I was planning to get a fifth tire for the spare. However, after some measurements, I realized it wouldn't fit. So I had the tire shop put the best of the worn 31x10.5x15 tires that was on there before on the spare, as it was the original tire from 1987...
Depends if you have a tow hitch. Get under there and measure!