that's a specific use case though, and it's also a cost vs. "enjoyment factor" issue.
I'd hope the true ********* wheelers have seperate offroad and on-road tires anyways, since I can't imagine life being too pleasant on the streets with true off-road tires. if you're really into wheeling you've probably invested heavily into the vehicle as it is (skids, winches, lifts, wheels,
tires) and having one or more matching spares is more for safety than enjoyment.
for majority of the time when doing on-road duties, as long as the spare is reasonably close in diameter to the 4 primary rollers I don't see any reason it HAS to be a total match. and as tj said, if you LSD's installed front/rear/both then you'll want to only do a 4-tire since a 5-tire always means you have a mis-matched sized tire on the ground. none of my vehicles have "matching" spare tires... mostly because they all ride around on expensive and directional tires; I couldn't do a crossover rotation even if I wanted to!
all but one have full size spares now also, but they're just good tires of a matching size on a proper size rim. the oddball is the "race car". since it doesn't see as much street duty it carries the factory donut spare. that and the spare well is too small for a full-sized spare, even of OEM wheel size.
to me and in my opinion, a matching full sized spare only is required for specific-use cases, like very poor terrain off-roading. otherwise a spare is there just to get you to a proper tire facility to either repair or replace the damaged tire. I'd hope most of the people in here aren't of the "ride the donut bald!" crowd!!
