Originally Posted by RAM EM
The rim diameter is irrelevant, it's the tire's diameter that matters. Your spare is relatively close in diameter to your 20's, and LSD's are forgiving enough for minor differences anyway. It's not like you have a locker or spool. You are completely safe to run your spare.
Thanks, I knew about the rim size and should of mentioned that I was concerned about the tire diameter.
Good to know though as I am planning a month long trip which will be into some remote locations, population wise and I did not want to be stuck if the tire diameter was a major concern.