I am buying Kerscher kcs wheels (8.5x18 and 10x18) for my M Roadster. I am not sure about the offsets. Roadstar wheel offsets are 41 front and 8 rear. I am thinking 39 front and 3 rear would be good?. I am also putting KW variante 3. Do i need spacers on the front? Does anywon know how wide are these wheels in the picture and what are the offsets? http://www.bmw-freunde-rn.de/_de/html/home.htm