I guess 15x7 is more common than I thought. Looks like there's a variety of 15x7 wheels in that style for 124s and 202s. Too bad they don't list ET -

http://www.ackerwheel.com/wheels-rims/Mercedes/index.html

No US 210 was delivered with 15" wheels, I'm sure of that.

Are these wheels for the Vanagon?

Sixto
87 300D