I bought and took possesion of my new 16" Schmidt wheels today:
Tunershop - Wheels - 16 inches - Schmidt Revolution Space Line
The great news is the wheels are designed for use with the stock Smart 3 lug wheel - no adpaters or spacers needed.
BobbyBRD recommended Tunershop in San Francisco, CA.
http://www.tunershop.com/Home/?TSID=8124c1c920ca99812eb4e6cd398a7dce
I also found Big O Tires, in Pleasanton, CA, uses Tunershop, DTH headers and various others suppliers to sell and install after market equipment for Smart cars. Ask for Dave Cherry.
Address: 3688A Washington St. Pleasanton, CA 94566
Phone: 925-462-7650