I asked the local SC for a set of 18” wheels with winter tyres as a spare set. Wanted the same Tesla wheels to avoid the ‘modification’ hassle with insurers. Tesla gave a prompt reply advising they were not available to order in the UK yet :-(
I thought it still counted as a modification if it didn’t arrive like that originally even when purchasing from the manufacturer additional official wheel sets.
Would be good to have clarification on this subject but probably varies from insurer anyway.