I dont know, this just seems silly to me. in the past four years, i have had three flats. every time, changed it out for the spare, drove to discount tire and in an hour its fixed and the spare is back in the trunk where it belongs.
then every time you buy new tire, you always have to buy five, fukc that, i would rather spend the money from the fifth tire and get four better tires (unless you OK with the wheels matching but not the tires)
or what happens if you get directional tires? then you either have a spare for the right side or the left side, but not both.
I travel on the highway a lot so perhaps I feel the way I do based on what my needs are. But even with that, if you bend a wheel, you have have no down time, if you will, while it gets repaired.
Apples and oranges at the end of the day. LOL.