For <i>chrome</i> wheels you can try an inexpensive metal cleaner called NOXON. It is a fairly thick white liquid that works very well and is available in most supermarkets. Takes about 1/3 the work to get results as compared to traditional polishes such as Simichrome.
Regardless of what you use to clean make sure to coat the wheels with a good wax. Perhaps the new "Wheel wax" is best.
'85 380 SL (sold)
'85 Carrera Flatnose
'71 280 SL Signal Red/Cognac