Like steel wheels, aluminum wheels are painted to protect them from corrosion. Some aluminum wheels are protected by a urethane or polyurethane clearcoat, allowing aluminum’s natural beauty to shine through, while other wheels feature combinations of clearcoat and opaque coatings. If the coating is intact, corrosion isn’t a problem, but exposure to sand, brake dust, dirt, and exhaust can damage the coating.
Whereas a steel wheel will rust on exposure to the environment, oxygen specifically, aluminum wheels corrode into a powder, leaving surface pits. On the sealing surface of the tire bead and the valve stem, corrosion causes air leaks. In wheel nut holes and on the rear face, corrosion skews torque application, possibly leading to loose wheel nuts.
Prevention vs Restoration
The best way to combat aluminum wheel corrosion and pitting is to prevent it in the first place. Keeping your wheels clean prevents abrasives from digging into the protection coating. Waxing your wheels once or twice a year is a great preventative measure. If you notice a small pit forming, sanding it out and recoating it can prevent spread.
If you have the time and tools, you can eliminate most minor corrosion and pitting without having to spring for a wheel restoration professional. Restoring an aluminum wheel takes time, two to four hours per wheel, but patience delivers the best results. Here are four basic steps you need to follow to restore aluminum wheels on your own.
Aluminum Wheel Restoration Steps
The best way to do this is with the tire and valve stem removed from the wheel, to prevent damage and make the job easier. Have a tire professional dismount the tires so you can work on a naked rim. Later, have the tires remounted and balanced.
- Jack up the car so the wheel can rotate. Use jack stands to support the vehicle while you’re working on the wheel. Rotating the wheel helps you to get to all its surfaces easier than on the workbench, floor, or ground. If the wheel nuts stick out past the face of the wheel, buy a single short nut and use only that one to hold the wheel to the car.
- Use masking tape to protect the tires, if necessary. Use degreaser to remove wax, dirt, brake dust, road grime, and let dry. Use polyurethane stripper to remove the clearcoat. Read and follow the instructions carefully for best results. After rinsing away any residue, let the wheel dry. Gloves and eye protection are a must for this step.
- Dry sanding will require a drill, sanding attachments, low-speed sander, and a range of sandpapers. Power tools deliver the most uniform surface quality. Start by sanding the wheel nut holes, slots, and outer lip with drill sanding drums or cones. Then, sand the center disc and face of the wheel with the low speed sander. It’s best to start at 80-grit. Going to 100-grit or 120-grit results in a machined look, while gradually stepping up to 2,000-grit gives a more polished look. Eye, ear, and dust protection are critical here.
- Finally, choose your finish – polish-and-wax or polish-and-coat. Either is beautiful and durable, though waxing requires a more upkeep. Use a quality aluminum polish either way, then finish with either hard wheel wax and buffing or your choice of paint or clearcoat. If painting or coating, allow 48 hours to cure before remounting tires.