To fix corroded alloy wheels, start by thoroughly cleaning them with a mild detergent and water. Once dry, sand the affected areas using fine-grit sandpaper to remove the corrosion. Apply a metal primer to the sanded areas, ensuring even coverage. Allow the primer to dry completely. Next, apply a matching alloy wheel paint to the primed areas, following the manufacturer's instructions. Allow the paint to dry thoroughly before touching or mounting the wheels. Finally, protect the wheels by applying a clear coat or wheel sealant. Regularly cleaning and waxing the wheels can help prevent future corrosion.