over sized tyres

Hi all, I have an A2 Tdi with standard Audi 17" 9 spoke rim which I think are 7J. I need to replace the tyres but I have a good set of Mitchelin's which can off of another car of ours which I would like to use. Normally these wheels use 205/40/17 but the one's I have are 225/45/17. Do you know...