They don't have spare tires. Instead, they have some kind of tire that continues to operate in a degraded mode, until they get to a dealer, who swaps out the flat for a new tire.
He blew a tire, in rural Upstate New York.
In today's lesson, we learn that upstate dealers don't stock S580 tires, and he's forced to leave his car that costs as much as some people's houses, at a podunk dealership, while a buddy gives him a ride.
Then, a week later, the dealer insists that he drive 400 miles, to pick up the car.
I believe that he did some screaming to Mercedes corporate, and got them to drive it down to Long Island.
For a flat tire.
There's nothing special about the wheels, so you can mount an appropriately sized "regular" tire and continue on your way. Worth the $250 to get on your way, I think.
I'd guess any non-dealer tire shop would have just sold your friend the tire and sent him on his way.
1. Non-standard tire - More expensive, won't be stocked, difficult to replace.
2. Reduced tire tread - Those grooves will receive more wear, overall the tires has maybe 1-5% reduced tread and contact surface.
3. Bumps/knocks - These pieces of metal are likely to be damaged and/or worn before they ever get used.
To me it would make far more sense to literally just bolt a cage to the alloy encase of snow, with some sensor to detect presence (reduce speed for safety) and knocking to indicate the user no longer drives on a snowy surface.
Another option could be to have some form of extension to increase the surface area of the tire.