Wow, that is interesting, and blows my theory out of the water...unless they priced them that way to ensure you cannot get a cheaper 21" wheel upgrade by purchasing a spare set. Where did you see the official pricing on the spare sets? And just to reaffirm, I do very much appreciate that we have the option to downgrade to the 19" wheel, or buy a spare set of 19" factory wheels. As you point out, both options are fairly unheard of with other auto manufacturers, and this speaks volumes for Tesla's customer experience. I know with my BMW for winter wheels I was sent straight to TireRack.com; I don't think a spare set of factory rims was even possible, or at least wasn't offered.