I plan on going with the 18in "Signum" rims from Bekkers. I saw them on a 300E and they were kick-butt. Contact "Tony" at www.bekkers.com.
He's a damn Mercedes wheel pro, he'll let you know how big you can go without the wheels sticking out or rubbing. I've seen the EVOII's, and I just dont like them that much. Check out those "Signum's", I think you'll like em...good luck!