They have a) service centers; b) the service centers allegedly provide parts and service for the car; c) they offer roadside assistance; d) the cars are not equipped with spare tires. Accordingly, the expectation is that the 'roadside assistance' would at a minimum a) direct you to a place that provides tires; and b) not direct you to a service center, when the 'roadside assistance' people should be able to talk in a straightforward manner with the 'service center' to get correct accounts of their inventory.
In essence -- because Tesla Roadside Assistance said, twice, "we have tires in stock for you now, at Service Center X", and were greatly mistaken. Basically, they must be using the equivalent of tin cans and a waxed string to call, speak with, and get real-time communication from one end of Tesla to the next.
Next time, I'll call the 'Psychic Hotline', instead of Tesla. Psychic Hotline knows more about Tesla's parts inventory than Tesla.