Be careful with your selection. The SLK200 is relatively underpowered, and fitting larger rims will probably decrease your acceleration and adversely affect handling and braking. Why? The larger wheel/tire combination will be heavier, unless you are fanatical about finding the lightest rims available. Those are probably forged, and not cheap. Heavier wheel/tire setups just add to unsprung weight, which is the enemy of responsive handling and underpowered cars feel it the most. I've kept the factory 16s on my SLK280 Sunhilde for just that reason; I don't want to compromise her responsiveness by adding weight at each corner. Yes, I can run her to the limits of grip on the factory tire size now that she is fitted with a B12 suspension kit. But unless I come into enough spare cash to get ultralight forged 17s, I'll change the grip level by fitting stickier tires next time around...Maybe Michelin Pilot Sport Cup or Yokohama Advan 048s (Lotus Elise tires) instead of bigger rims.