Unfortunately the SLK32 was a very rare model (equivalent to SRT-6). However AFAIR a SLK320 and a Crossfire use the same front brake rotors so the '98-'04 SLK230/320 16' rims should fit.
OTOH the '04-'09 SLK350 came with 17s stock and the base SLK280 came with 16s. After '09 the SLKs went to a 14mm lug bolt.