I'd bypass the salesman and go to the service department and ask to speak with a tech. They'll be able to tell you. I'm surprised none of the people you talked to at a dealer were very helpful in that regard. Failing that, possibly a good high-end tire/wheel shop would know for sure.
I've never looked into it as I've never bought wheels for a car, mine have always worn what they came with...this may change as I'd like a set of steelies with Bridgestone Blizzak snow tires for next winter...
Todd in Beerbratistan