Bruce,
I found one made of silicon from a guy in Germany, fits very well and I'm about to do my new hub caps. He has them for smaller caps or for the newer large caps. I believe I paid about $100US including shipping. Here is his email address (CBS.BAUMGARTNER@onlinehome.de).
K&K has new hub caps for about $27 ea. for the smaller ones. Orginal Mercedes all chrome. I think I need to etch the part to be painted though. Anyone have thoughts or ideas how to do this?
Aloha,
Jim Saylor
Kauai, Hawaii
'65 230SL