polishing rebels
Mother's Chrome polish does this. ANy type of car wax or sealent will work as well.
I bought a set of these last summer, took good care of them (waxed them more than the car), parked it for the winter & the chrome was junk within a year (the tires outlasted the wheels). I got them replaced under warranty & have waxed them every week so far. Hopefully they will still look good next summer.
I bought chrome instead of polished wheels because I did not want to constantly maintain them on my daily driver.... do not let them see any road salt or you will likely have to paint them next year.

