There's a "tire database in the sky" that contains every vehicle with all the tires certified for it -- that's what trips us up, as "Spyder" is not in that database. I think there's a federal requirement for that database.

IIRC, I ordered my Kumho's from Tirerack.com. When ordering, there was an option (a box to check) that said something like "this tire matches what's already on my car." That's the escape clause. When I got the tires, there was a statement on the receipt to the effect that "owner assumes liability."

If you take the Spyder to a tire dealership, many will balk at working on a Spyder. But if you just take in the wheels, they have no idea what the vehicle is, so they're happy to get the work.

I read somewhere but can't confirm, that the three-hole pattern for the front wheels is the same as for a Smart car.