15" are hard to find. Made by Fuchs (original MB), ATS, ARC-Alurad, Centra, Ronal (last 4 are aftermarket). ET23 to ET25 range of offset figures. Best, is Fuchs because that's 1. original and 2. they're forged so the wheels are stronger.
As long as they're not chromed you should be okay. Chrome has a tendency to leak air out after a while.
You've probably already seen my 15" Centra Bundts before:
More here
http://www.benzworld.org/forums/w123-e-ce-d-cd-td/1400649-different-versions-15-bundt-wheel-design.html