Sorry, my wheels aren't like the picture I referenced earlier. See attached pic for the actual wheels on my car. I'm not sure what year SLK they're from or the width. But they're 16" and they clear the front brakes.

When I was buying those wheels I tried searching for whether 16" wheels would fit the car and I couldn't find a conclusive answer, so I actually test-fit them on before buying them. Hopefully this will help someone else. The rears are a bit "sunken in" compared to the stock wheels, but it's fine for winter and doesn't look too out of place. The only thing I had to do was get shorter bolts for the rear wheels (I got original SLK bolts) as the Crossfire bolts were too long with these wheels, went in too deep, and were interfering with the parking brake mechanism.