Mercedes-Benz SLK Operator's Manual page 338

Wheel and tire combinations
336
certain circumstances, require rims of the
appropriate size. The sizes of the approved
winter tires may deviate from that of the
standard tires. This is dependent on the
model and the equipment installed at the
factory.
The tires and wheel rims, as well as further
information, can be obtained at a qualified
specialist workshop.