Picking a custom wheel finish is not only a choice of aesthetic. Depending on the finishing method used, a wheel's finish can affect how well it holds up to the elements and how often it needs to be maintained. Below are some common types of finishes used on custom wheels today:
Machined finishes are frequently used for alloy wheels because aluminum alloy is a fairly easy material to work with. A machined wheel finish is applied by spinning a wheel on a computerized lathe that precisely cuts a thin layer away from the wheel's surface to give it a clean, metallic look, with very thin lines similar to a CD. Often, a clear polyurethane top coat is applied to the wheel after machining, which seals the aluminum from oxidization.
Some wheels are fully machined, while many others are only machined on the face, lip, or flange. Machined wheels can be maintained by periodically washing them with a mild soap and water solution. This reduces the wheel's exposure to brake dust, tar, and other substances that might cause the clear coating to deteroriate over time.
Most custom wheels today are painted to provide visual appeal. Painted wheel finishes may be applied through spray-painting, or through an innovative "powder-coating" process that entails baking the color directly into the metal. Painted wheels generally have a clear top coating that keeps the paint intact and preserves its appearance.
Painted wheels come in many different colors, including gray, bronze, red, blue, silver, and multiple shades of black. This variety provides drivers with considerable freedom in customizing the looks of their vehicles. For further customization potential, painted wheel finishes are often partially machined to produce a variety of stylish, creative patterns. As with clear-coated machined wheels, painted wheels can be kept in good condition by periodically washing them with mild soap and water. Try to avoid using acidic cleaners or strong polishes that may damage the clear top coat.
A polished wheel finish is one where the wheel's aluminum surface is buffed and smoothed to a mirror-like shine. Since polishing doesn't add any weight to the wheel, polished wheels are desirable for racing and tuner applications that require lightweight wheels. Many classic wheels are polished.
Polished aluminum wheels can be maintained through regular buffing and waxing. However, they are also more prone to scratches or dents. Some polished wheels do not come with a clear top coat, which allows them to be cleaned with strong metal polishes, but also makes them more susceptible to oxidization and tarnishing unless polished regularly. For this reason, polished wheels should be cleaned and repolished frequently to maintain their appearance.
Chrome wheels owe their popularity to their bright, exquisite luster. For a standard chrome-plated finish, an aluminum wheel is coated with layers of copper, nickel, and chromium to form a protective "armor" that insulates the wheel from corrosion. A chrome finish not only offers premium levels of aesthetic appeal, but is very hard and resistant to scratches or dings.
While chrome plating is durable, it is also heavy and adds more weight to the wheel than other finishes. Chrome also tends to corrode when exposed to salt, such as road salts used for de-icing roads in winter, or the salinated air in coastal areas. For this reason, chrome wheels should be cleaned right after driving in snow or replaced for the winter to prevent cracking or peeling.
In recent years, wheel manufacturers have turned to PVD as an alternative to traditional chrome-plating. Short for physical vapor deposition, a PVD finish gives the wheel a durable metallic coating with a similar sheen and luster to a standard chrome finish. Unlike traditional chrome wheels, however, PVD wheels hold up better in winter conditions and exposure to salt. A PVD finish also adds less weight to the wheel than a chrome-plated finish.