Bought a used tire on Ebay that matched the set that came on my Yukon a few weeks ago, and then picked up a 20" rim from a 2009 Nissan Titan at a salvage yard last weekend.
Today I had them mounted and balanced as a full sized spare that I don't have to worry about messing up the AWD, and that I feel comfortable using if I had to put it on while towing.
View attachment 72582
It fit nicely in the place of the original 16" and doesn't hang any lower then the rear differential so I didn't loose and ground clearance.