30" would work. I'm getting some new 32" BFG's and have one of those donuts in the back. Need it for a just in case type situation. What would you want for it? Does it have a wheel too?
I need to look for it tonight, but it should come on a stock jeep wheel and how much... hmmm $20?? from what I recall it's in real good shape with plenty thread, but I do have to find it first to confirm.