Thanks, all.
I replaced the spare with a new one the same size as the ones on the truck. The 265 fits in the spare space with plenty of room to spare. I would love to rotate the spare with the others but the spare wheel is steel and the others are forged aluminum. I thought about getting another OEM aluminum but the spare wheel was all chipped up, I guess with road gravel and such.
Oh, and my spare was completely flat. I had last checked in the fall. Someone on here used to remind us to check air in the spare at the same time you change clocks. Good idea to check yours if you haven't.