Alloy is a dull, gray metal and is the most common type of material for making vehicle rims. Although alloy is metal, it can still become damaged. Alloy rims become scratched, dented and scuffed from debris in the road or by driving too close to curbs or solid objects. The rims can also become pitted, which leaves small holes with rough edges on the rims. Fix alloy rims by properly preparing and painting them to look like new.
Sand the damaged area with 220 grit sandpaper. Hold the sandpaper flat against the surface and sand evenly in several directions so groves don't form in the rim. Sand until the area is smooth and no rough areas can be seen or felt by your hand.
Apply body filler to any low areas on the alloy rim. Use a small squeegee to spread the filler across the low area and smooth it. Let the filler dry for thirty minutes or until it becomes hard. Sand the filler with 220 grit sandpaper until it is smooth and level with the surrounding surface of the rim.
Sand the repaired area with 400 grit sandpaper and water. Hold a running water hose above the sandpaper or dunk the sandpaper in water frequently to keep it soaking wet. This prevents the buildup under the sandpaper from leaving deep scratches in the rim. Repeat this step using 600 grit sandpaper also. Rinse the rim and allow it to dry completely.
Cover the lug nuts and air valve stem with masking tape to prevent overspray from sealing them shut. Tape may be placed over the sidewall of the tire if the repair is being made on the edge of the rim.
Spray the repaired area with gray spray primer. This puts a solid base color over the body filler and allows the paint to adhere better to the rim. Hold the spray can six to eight inches from the surface and spray left and right, using one light coat to cover the repaired area. Let the primer dry for thirty minutes.
Apply three to five thin coats of spray paint to the primered area. Most auto parts stores carry spray paint made specifically for painting each different type of metal rim, so getting a correct match is easy. Spray the paint using the same spray techniques as with the primer. Wait five minutes between each coat and wait four hours before handling the rim.