The rule/law in Germany is: The car MUST be overwhelmingly original, as it was when manufactured.
I got gigged on the Formula rims, the inspector knew that they were not original on the Coupe, but thankfully I had the original rims also, and only have my winter tires on the offset Formula rims. They are real stingy about the original state of the car here. You can register mods here in Germany also (expensive), just not as old-timers. The advantage of registering as an old-timer is cheap insurance and much lower car tax. Makes no sense if you ask me.
\D