Since u stated u only need rears you should get the same brand and tread style as the fronts.
If you decide on buying all four then Pirelli or Michelin. I think Pirelli P-Zero handle great but Michelin Pilot Sports handle good and will last longer then the P-zero. Asking people which tires to buy is like asking which synthetic oil is the best, the answer will vary from person to person.
I took those turd ConiSports off my car w 7000 miles and put a set of Michelin Pilot Sport 2s on. WHAT A DIFFERENCE. The car handled better, tracked straighter, and was quieter on the highway. I have no idea why MB uses Conti's in the first place. My .02.
BenzWorld.org forum is one of the largest Mercedes-Benz owner websites offering the most comprehensive collection of Mercedes-Benz information anywhere in the world. The site includes MB Forums, News, Galleries, Publications, Classifieds, Events and much more!