Why do I get the feeling that in X number of years (hopefully X is a large number), when you pass away, your next of kin are going to have to deal with a huge mountainous pile of new or slightly used tires?
I don't have any extra tires for my vehicles except for one factory Dunlop tire with approximately 15,000 miles on it sitting in my garage. When a factory Dunlop tire failed, I bought a new pair to keep the tires the same on an axle. I kept the other Dunlop as an extra should that happen again.
If I sold a vehicle, it would come with 8 tires (4 summer & 4 winter tires). I don't have anything extra beyond that at this time.
I actually don't keep stuff that I don't use for very long.