What are the Types of Rims On The Market?
Wheels these days come in a variety of types. Understanding what they are made of, and how, can help you choose the best rims for your cars. Whether your motivation is style, price, or performance, the type of rim you choose can have a big impact on your relationship with your car.
The most common way people classify rims is by the material used to build them. The most common materials are steel, aluminum, and alloy. Even carbon fiber is available these days, though it is more rare and much more expensive than its metal cousins.
You might also think of chrome wheels when you think of rims, but chrome is just a coating, not the material your wheel is made of. Most chrome rims are aluminum underneath. Also, most aluminum units are made with nickel as well, and so are technically alloys. However, the wheel we refer to as alloy rims are different because they can be made with anything from aluminum to magnesium. These alloys are usually stronger and lighter than aluminum rims.
How Rims are Made
Another major difference between wheels is how they are made.
Steel is the cheapest and easiest to make. They’re also the strongest. On the downside, they lack style, and they are heavy. Steel rims are pressed into shape from a solid brick or tube of steel.
Aluminum and alloy wheels are cast or forged, which is why they can be designed into interesting shapes. The types of casting have an impact on strength and weight of the finished product.
Gravity casting is where molten alloy is poured into a cast and left to settle under the pull of gravity. Pressure casting is similar but applies some compression to the molten liquid. The result is a denser, and therefore stronger rim.
Flow formed wheels are cast, and then placed in a machine that spins them, while applying heat and rollers to shape the final product. This adds strength and lightness to normal cast wheels. This is the most common form of construction for OEM units.
Forged wheels are the strongest one-piece wheel. They are made by squeezing a solid bar of aluminum into a high-pressure machine. They cost a lot to make, because the tooling set up is expensive, but the result is a highly dense, ultra-strong, and lightweight rim.
Two- and three-piece wheels
Most of the wheels you see are cast in one single unit, however there are multi-piece offerings on the market. In two-piece examples, the face is screwed to the outer rim, aka barrel. In three-piece examples, that outer barrel is split and can sometimes even be adjusted for width.
These options are usually heavier than single-piece units, but they add strength, style, and in some cases adjustability. High-end versions claim to be lighter on the outside, which can help with acceleration if the overall wheel weight is lighter than factory.
A variation on this theme is the older-style, wire-spoked wheels. Most famous on classic cars like Jaguars, these wheels use many spokes weaved together to join the outer barrel and center.
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