hi,
in order to fit aftermarket non smart specific wheels they will need to have a PCD of 5x112. you will have to get the 7"x17" ones. thats the biggest. the 7.5"x18" are too big for the smart. i've just checked on momoshop.co.uk and they DO NOT come in this PCD.
you say smart madness has fitted them - are you sure they are the EXACT same wheels?
aftermarket wheels with adapters will ONLY work with a PCD of 5x112(mercedes).
UNLESS you do a hub conversion - where you replace the hubs and drill holes into the new ones with any PCD you like.