The SLK320 trailer hitch will not work. Trust me I tried going that route before I built my own. My friend has an SLK with trailer hitch and I climbed underneath it to look. The hitch mounts to the spare tire well on that car and we don't have one of those on our car that sticks down low enough because of the center exit exhaust. Here are a couple pictures of my custom hitch to tow my race tires.

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