Yes, I tried 235/40R18 on 18x8.5 and 265/35 on 18x9.5with the 5 mm pads and they were OK...
on the fender. However, the wide SO3s rubbed a little on the inside of the wheel well in the rear about 4 inches in front of the springs. No fender rubbing so I would expect that 225 and 255 would be fine. This is the exact setup I am going with. The story may change with lowering springs however.
Go to http://www.TireRack.com and "Shop For Wheels"
Since you don't really seem to know what you want.<br> <br> This will show you all the wheels they carry that fit your SLK. You can get an idea of looks and know that the wheels fit correctly. They offer complete wheel/tire packages too.<br> <br>