Mich means Michelin, the producer of the tyres.
The German text in item 19, you can't read:
19 Bereifung 5-fach
Bereifung means tyre
5-fach means 4 wheels + spare wheel
Fabrikat means Producer
In the 70ies and 80 Mercedes delivered the brand new car with different
producer of the tyres.
So, have lock in your trunk. When your spare wheel is original, then
you should have installed a michelin tyre on the wheel.
Greetings from Germany