Whether you are looking into buying a new car or simply replacing a bent rim, there are some rim basics that you really ought to know to ensure that you make an informed choice. With this in mind, let’s brush up on our rim knowledge. I will go over the anatomy of rims and wheels, as well as the different types of car rims out there and what they are made of and how, with links to some popular brands for you to check out.
Rim and Wheel Anatomy
The outermost visible part of a wheel consists of:
- A hub
- A bolt circle
- A wheel disc
- A valve stem
- A rim
The hub is the center part where the wheel attaches to the suspension.
The centers of the lug bolts describe the bolt circle. Its diameter, the Bolt Circle Diameter (BCD), and the number of bolts together make up the bolt pattern.
For instance, five lug bolts with a 120 mm BCD equal a 5 x 41200 mm bolt pattern. Because bolt patterns vary between different brands and models, you need to know your vehicle’s bolt pattern when looking for new rims.
The wheel disc is the part that connects the hub with the rim. Visually, it makes up most of the outer surface of the wheel. The disc and the rim can either be detachable or made from one piece of metal.
In the past, early car wheels had spokes made out of wood or wire that joined the hub and rim. Today, wheel discs do that, but still often come with stylized spokes. Their designs vary widely, and you can get really creative with them.
Together, the disc and spokes support the rim and help resist impact from the road.
The valve stem is the small hole through which you pump air into the tire.
Finally, there’s the rim. Its main role is to support the tire, seal it onto the wheel, and ensure a proper fit. The rim is also responsible for trapping air within the tubeless tire.
Types of Car Rims: Materials
Manufacturers make most types of car rims from either aluminum alloy or steel. The material of your rims will have a huge impact on both their appearance and performance later on.
Aluminum rims are also known as alloy rims because they are made from aluminum and nickel alloy. They are, by far, the more popular type for two main reasons:
- Alloy rims are much lighter. That results in much better acceleration and overall performance.
- Alloy rims look a lot better. Unlike their steel counterparts, alloy rims come in a wide range of designs, shapes, and forms. They can also have many different types of finishes, such as paint, polish, chrome, or powder coating. All that allows for almost endless customization.
On the negative side, due to their great looks and stellar performance, alloy rims are much more expensive than steel ones.
More importantly, alloy rims are more prone to bends and cracks. While the nickel in the aluminum alloy makes the rim heavier and more solid on the road, unfortunately, it also makes it more brittle. In contrast, a lower nickel content results in a lighter rim that bends easily.
Finally, alloy rims are more vulnerable to surface damage from scrapes, scratches, salt, and acid cleaners.
Steel rims might be somewhat less glamorous, but boy, do they do the job.
They are much heavier than alloy rims, which, in normal conditions, is a disadvantage, as it inhibits acceleration and swiftness.
However, the extra weight also lowers the center of gravity of your car and makes the tires bite the snow harder. In combination with the reduced acceleration, that makes steel rims a great choice for the winter.
Furthermore, steel rims are much stronger than alloy ones. It takes a lot to bend them, and even more to actually crack them. That makes steel rims perfect for vehicles that do heavy-duty work.
Unfortunately, however, the appearance of steel rims is more on the utilitarian side and won’t turn any heads. You may buy wheel covers that make steel rims look like alloy ones, but they are fragile, come off easily, and pose a danger on the road. And in all earnestness, they don’t look that good either.
Certain manufacturers are now trying to develop steel rims and wheels with a chrome finish. They chrome-plate a tin overlay and then glue it onto the wheel.
On the bright side, steel rims are rather inexpensive and will serve you well for a long time.
In terms of sizing, steel rims generally only come in a diameter of 16” or less.
Types of Car Rims: Production Methods
The material that car rims are made of is not the only factor that determines their appearance, price, and performance. Another key factor is the production method. So far, I’ve covered the “what” of car rims. Now, let’s explore the “how.”
Casting refers to the process of heating metal at a very high temperature, melting it, and pouring it into a mold or cast to form the desired shape.
Most aluminum rims are cast from a single piece of metal together with the rest of the wheel. There are four main wheel-casting methods.
The most straightforward wheel-casting process uses gravity to fill up the mold once the molten aluminum is poured. Due to its simplicity, this method is rather inexpensive. It is also quite useful for achieving more intricate designs.
On the other hand, this process only relies on gravity to fill up the cast. As a result, the metal is not as tightly packed as with some other casting methods.
To achieve higher density and strength, more metal needs to be poured into the mixture. That leads to somewhat heavier rims and wheels.
This method uses added pressure to move the molten metal around the cast and pack it in more densely. That results in wheels and rims that are both lighter and stronger than those produced via gravity casting. Still, the higher the pressure, the better the results — and the higher the price.
People have probably told you that forged wheels are the best, and they are not far from the truth.
Forging is a process that forces a chunk of metal between forging dies under very high pressure. That makes for an end product that is uniquely dense and strong, yet very light. It also means, though, that forged wheels are very exclusive and rather expensive.
Rim-spinning, also known as flow-forming or rim-rolling, is a highly specialized, multi-step process. First, the molten metal is cast under low pressure. The casting is then reheated, spun, and pressed using steel rollers to achieve the final shape of the wheel.
The combined action of pressure, heat, and spinning results in high-performing, lightweight wheels with a strength similar to that of forged wheels at a fraction of the cost.
Sports and racing car manufacturers often use this production method.
As their name suggests, multi-piece wheels comprise two or three parts that join together to create the finished wheel.
They can be made using different production methods. The centers of the wheels are normally either cast or forged, and the rims are usually spun. The separate parts are then bolted, welded, and sealed together. That makes it possible to create a much wider variety of custom wheels than by just using one production method or single-piece wheels.
Three-piece wheels are more prevalent in the 17’’+ diameters. Two-piece wheels offer fewer customization options but are generally much cheaper and more common on the market.
Types of Car Rims: Sizes, Styles, and Bolt Patterns
Your new, shiny rims won’t serve you any good if they are not the right match for your vehicle. In addition to rim materials and production methods, there are a few more factors you need to keep in mind when it comes to car rims.
You must always, always make sure that you know the size of your wheels when buying new rims. Do not go for a set of 22’’ rims just because they look great if you have 18’’ wheels. Just like with shoes and clothes, always shop for the body you have and not the accessories you want!
If you are lucky enough to have a sports car, check the size of both the front and rear rims. Oftentimes, the rear rims of sports cars are larger than the front ones.
Nowadays, there are enough types of car rims out there to suit all tastes. However, if yours is more on the alternative side, make sure you don’t pick something extravagant at the expense of efficiency and functionality.
Furthermore, certain styles of car rims may require you to also buy new tires to fit them. Unless you have money to waste, always double-check that your rims of choice match your existing gear.
To make sure the rims are compatible with your car, check the manufacturer’s instructions and consult with a professional.
Last but not least — let’s discuss the bolt or lug pattern. It is the most important issue when it comes to fitting wheels and rims. Simply put, if the bolt pattern of your car does not match the bolt pattern of your wheel, it just won’t fit.
As bolt patterns come in a rather wide range of sizes, always double-check yours. Furthermore, keep in mind that manufacturers write bolt patterns in inches as well as in millimeters; this can sometimes lead to confusion.
While it is common nowadays to speak and think of car rims as fashionable accessories, they are, in fact, an absolute necessity. If you own a car, you are likely to find yourself shopping for car rims one of these days.
However, with so many types of car rims available on the market, you can easily get overwhelmed. Fortunately, this article should help you get a better grasp of the different types of car rims and their ins and out so that you can make informed choices about your vehicle.