See my earlier post...
"In theory, yes. However, people still do so. However, changing a set of wheels for a different set of wheels is less likely to cause issues with the police than fitting tyres which are too small for the wheels. But as is widely known, changing wheels from standard fit is also insurance notifiable, which brings you back to the point Jay made (sort of), where the change is entirely acceptable to the insurers but is in contravention of the regulations."