My Suburban has the G80 "locking" differential. I checked my spare tire the other day, and it's smaller than the other four tires. I know some differential traction aids don't like mismatched tires on the same axle. How about the G80? Are mismatched tires going to fool the G80 into thinking that one tire is spinning and cause it to lock up? If so, I either have to get a proper sized spare, or always put the spare on the front.