Polished aluminum wheels have a classy, timeless look about them. For trail use, they've got another advantage: Because there's no paint over the aluminum, they'll stay the same color if they get scratched.
Even though there's no paint to scratch or chip, polished aluminum wheels can still get weather-beaten and dingy. Aluminum won't rust, but it can still oxidize. Instead of rusty red, oxidized aluminum turns a dingy light grey.
Mothers has an easy way to keep your polished aluminum wheels looking new. Using Mothers PowerBall buffing tool and PowerMetal polishing compound, it's possible to erase oxidation and minor scratches. Deep scratches will usually remain, but at least they'll have a shiny luster.