Wheel Finishes: Spotting the Difference

They’re all round, but they’re all different!

Wheels – hard-working components that need special looking after. Not only can their appearance make or break the look of a vehicle but their condition can also significantly impact on resale values. With so many different types of wheel finishes on the market and with such a myriad of products available, determining the right one for your wheels can be tricky. In this article, we look at some of the popular types of wheel finish and highlight the differences which determine the best practices for keeping them looking ‘as new’.

These days, many cars have alloy wheels, made from either aluminium or magnesium mixed in with traces of other metals to give them greater strength. Aluminium alloy wheels are found on most modern cars; magnesium alloys can be more brittle than aluminium alloy wheels and as such are typically found on high-end sports cars or race cars where this is outweighed by being lighter, a typical ‘Mag Alloy’ wheel weighs between 5-9kg.

Types of alloy wheel finishes vary greatly. Some of the most popular are:

• Painted & Lacquered – standard for most cars, e.g. Audi, BMW, Ford, etc.
• Powder Coated – a more durable finish
• Anodised – used on some aftermarket custom wheels and lightweight race wheels
• Diamond Cut – high shine look commonly used by manufacturers to highlight their top of the range models
• Split Rims – often seen on Porsche, BMW and VW, very popular in the custom scene
• Chrome – mostly found on classic cars

Just to confuse matters, some of these finishes can be combined. Many wheels, whether they are diamond cut, split rims, chrome or powder coated, have a lacquer applied to them during the finishing process in order to guard against corrosion.

As wheels tend to be the dirtiest part of the car, no matter what the finish, it’s a good idea to use a dedicated wheel wash bucket, wash mitt, safe wheel brushes and drying towels. That way you can be sure to minimise any chance of cross-contamination from the wheels to the bodywork when washing your car.

Wheel finishes and the differences in care requirements:

Painted & Lacquered

Painted and lacquered wheels can be treated in a similar way to bodywork. Wash chemicals with extremes of pH should be avoided. Frequent contact with highly acidic or alkaline products, such as those typically found at the popular supermarket hand car washes will etch the lacquer and potentially cause blistering and peeling. A ferrous contamination remover should be used to ensure any metal particles are neutralised before being safely rinsed off the wheels. Ferrous contamination is caused by tiny particles of steel brake discs shredding. The hot slivers bond to the surface of the wheel and if not removed will potentially cause pitting in the wheel surface. The wheels should be cleaned regularly and provided the wheels are protected, a dedicated wheel cleaning product is usually sufficient to remove any build-up of dirt, brake dust deposits and grime.

Protecting lacquered wheels is in principle similar to sealing paintwork which is also lacquered to add shine and protect the underlying paint from UV-fade, industrial and environmental fallout and wash swirls. This type of wheel finish can be protected with either a wheel wax or ceramic sealant, however, a ceramic sealant is far more durable and can help protect against hot brake dust from compromising the lacquer.  It is important to note that before a wax or sealant can be applied the surface should be first refined by hand with a cleanser polish and then, in the case of ceramic sealants wiped with a residue remover to ensure a satisfactory bond with the wheel.

Powder Coated

Powder Coating is applied as a dry powder. The main difference between a conventional liquid paint and a powder coating is that the powder coating does not require a solvent. The coating is typically applied electrostatically and is then cured under heat to allow it to flow and form a durable “skin”. This process creates a hard finish that is tougher than conventional paint. Powder Coated wheels are lacquered in the same way that painted wheels are and as a result can be cleaned and sealed in the same way.

Anodised

Anodising involves using an electrochemical reaction to force an increase in the thickness of the oxide layer on the surface of the wheel. As such, the finish is not a separate layer, but integral to the wheel. Anodised wheels are sealed using a chemical process, typically have a textured feel to them and can be produced in a number of different colours. Although naturally hard wearing, weather and corrosion resistant, anodised wheels should still be regularly treated for iron contamination and cleaned to preserve their finish, as once they become stained they will need to be chemically stripped in order to be refurbished. The best way to clean them is simply to wash with a mild car shampoo. As Anodised wheels are chemically sealed during the anodisation process they do not normally require a wax or sealant.

Diamond Cut

Diamond Cut wheels are first painted in the selected colour and then baked in an oven. Once dry the wheel is mounted on a CNC (computer numerical controlled) lathe so that the face of the wheel can be machined to achieve the metallic diamond cut pattern. The wheels are then sprayed with an Acrylic Lacquer to finish the look.

Although lacquered the diamond cut finish can be susceptible to damage. If water gets under the lacquer it stains the bare metal a milky colour – hard to get to without the lacquer being completely stripped. Diamond cut wheels cannot be continuously re-cut as each time they’re machined, some of the metal is removed and eventually, this would compromise the structural integrity of the wheel. Cleaning them with a mild car shampoo or pH neutral wheel cleaner is the safest way to prolong their life. Avoid using any acid or alkaline-based wheel cleaners as eventually they may cause discolouration and corrosion of the rim. As the edges can be very sharp, towel drying them may result in threads or lint becoming caught on the edges. Drying with an air blower is a great way of ensuring they’re completely dry and therefore avoiding this problem.

It’s imperative to be able to access areas where corrosion or staining begins to occur. Ceramic sealants are incredibly durable and can last upwards of two years. In spite of their effectiveness when it comes to protecting from contamination, the slightest damage from a stone chip, etc. means salt ions, due to their small size may find their way under the coating. Once they have compromised the sealant the ions will then attach to the bare metal underneath and begin to corrode. Ceramic sealants require machine polishing to remove so any surface issues that arise are difficult to treat. Therefore, wheel waxes and polymer sealants are better choices for this type of finish as they can be removed to allow access to any areas that need attention.

Split Rims

Rather than being constructed from a single piece of aluminium alloy, split rims are made up of two or even three pieces of alloy bolted together. They are often lacquered as they’re can be susceptible to corrosion and rusting, although with some split rims the various sections will have different finishes. It’s not uncommon to see an anodised centre-piece with a lacquered middle and a bare metal rim around the outside. Split rims are characterised by visible bolts holding the various sections of the wheel together and these can be found either at the front or the rear of the wheel. Even when lacquered these wheels are not usually found on everyday use vehicles as they’re high maintenance! As with diamond cut rims, split rims should be washed with shampoo or pH neutral wheel cleaner and rinsed carefully before being dried thoroughly. Again, an air blower is the most effective method of ensuring the wheel is completely dry, front and back.

Ceramic sealants are not compatible with bare unlacquered metal and therefore it is advisable to protect these types of wheels with a high quality wheel wax.

Chrome & Wire Wheels

Typically found on British classic cars as intricate wire wheels and also very popular with the American classic car scene, chrome wheels have a high shine but are tricky to look after: using any alkaline-based cleaning solution will result in staining of the metal. The staining can be removed by polishing, but it’s best to avoid the problem by simply using a car shampoo to clean them. Due to their propensity for corrosion, regular cleaning is an absolute must. Although many chrome wheels on classic cars are subsequently lacquered by their owners in an effort to protect their appearance for longer, it can be difficult to tell without a direct comparison with a non-lacquered wheel. As a result, it’s best to wash with a mild shampoo, using a small, soft brush to dislodge contamination and blow dry with an air dryer to avoid water spot marks. Alternatively use an Aqua Gleam, a de-ionising filter that removes the impurities in water which cause the spot marks and so eliminates the requirement for drying!

Chrome finish is delicate, but it’s best to protect it with a wax or polymer-based sealant to allow easy access to the surface if rust spots appear as rust very quickly eats through the chrome surface. Using a mild shampoo to wash the wheels should prevent wax or sealant removal so the process may not need to be done each time the wheels are cleaned.

For our detailing clients, you can be assured that we know the best type of cleaner or protective sealant to use on your specific wheel finish. If you have any questions, get in touch with the Bellissimoto team on 020 7237 6505 or drop an email to detailing@bellissimoto.co.uk and we will be able to advise you.