Why would someone chrome aluminum wheels Sam?
To make them shiney and give them protection. Polished aluminum wheels fade after time, and you have to hit them with the polishing clay to keep them shiney. Chromed aluminum never fades or rusts. That is why it is better then chromed steel or polished aluminum.
Those very expensive chromed wheels you see for cars, trucks, bikes, etc, those are chromed aluminum. Chrome steel are the cheap ones. Polished aluminum are more expensive then chromed steel, but not as expensive as the chromed aluminum.
The polished aluminum are the "budget" aluminum wheels you can buy for less then 100 bucks a wheel. Chromed aluminum wheels are like 300 a pop or more. For bikes, they are 600 to 800 bucks a pop.
The chrome also acts as a shell to help protect the aluminum, it is harder to ding and scratch a chromed aluminum wheel compared to just a polished aluminum wheel.