How to remove brown dirt/ residue off aluminum inner barrel?

[noelbnetz]

I recently got these work wheels and wanted to fully clean them before putting them on my car. The outer barrel is perfect and clean however after washing my wheels the inner barrel is still dirty with large areas of brown and little spots of brown that seem impossible to remove. I read that work wheels are aluminum and i know that aluminum doesnt rust but corrodes, so Im skeptical to believe it is rust.

Does anyone know how to clean the inner barrel? Thanks

 

[Snoopyslr]

It's most likely brake dust that bonded to the wheel. You could try a product like Iron X to neutralize the oxidation.

I always paint my barrels black. They are just too much of a PITA to keep clean.