Spare tire size questions

[JRZEE2000TR4LTD]

I have 275 70 17s' on my truck. I would like to put the same size spare underneath where the original goes. Will it fit? I have an OEM tow bar. Where would I find a rim and/or tire/rim asy? Would it be ok to use a 265 70 17?
Thanks!

 

[Unner]

I fit a 255/75/17 under mine as a spare. Same height as your tires. What really matters is what hitch you have. There are many different versions, the original mine had wouldn't fit a 265/75/16. But my new one will fit a 255/75/17...