Wheels have to be within 5% of the rolling diameter to access the homologation tests, where they measure the width, the track etc.. a ballache..
UK Mot tester are more scrupolous, acknoleadgeble and then less permissive than EU testers..
I am not so sure! think they are pretty strict here as the test stations are all state owned. well at least until last year, when the industry opened up for independent chains.
Either way, I dont think its going to be too big of a deal.