You have a real problem. There is only the one tire in the original tire size - Goodyear Wrangler SRA.
Detail: The original tire is an LT inflated to 60 and 75 psi. They have Load Indices of 121/118S.
You should NOT use any tire without the letters "LT" in front of the size, nor should you use any tire with a lower load index.
I see that there are LT275/65R20's - but those are physically larger. There is probably enough room, but unless someone actually measures the fenderwell, you can't be sure.