Wheels: What's Your Type?
Steel with a cover or hubcap
Manufacturers often use painted plastic covers. In the past, chrome hubcaps were common. The painted covers may be treated with the same auto wash and wax used on the body of the car.
Chrome plated steel
These are the shiny chrome wheels common with after market products. Though a hard surface, chrome wheels require meticulous care if you want to keep their shine.
Aluminum
Most auto manufacturers offer aluminum wheels that are anodized or covered with a clear coat (the same kind of clear coat used on the car's body). Some aftermarket wheels do not have a coat of protection and are especially susceptible to brake dust and road grime. You can apply a coat of wheel dressing or wax to help keep them fit.
Bare aluminum
Bare aluminum wheels are especially shiny but do not have a clear coat protection. Use a layer of wax or wheel protection to help prevent damage.
Magnesium
These are the lightest wheels made and sometimes seen on high performance vehicles. They require frequent care since they are easily damaged by road salt, brake dust and brushing up against a curb.
Source: Black Magic