I'm a newbie and I'm already in the mire ! My recently purchased 2008 2.o Roadster is fitted with 17" wheels. I've purchased some used genuine 18" 7 spoke wheels with tyres and they don't fit. The hub is a tiny bit too big for the wheel. I thought that I did all my homework - 18" 5x112 et 52's will replace 17" 5x112 et 47's - except they don't. Anyone any ideas ?