One of the first changes many owners make to their caris selecting an aftermarket wheel. There are many reasons for changing your wheels including:
Whatever your reasons you'll want to find a set of wheels that fit right for the right price. There are a vast array of options to choose from but not all wheels are created equal. To make a wheel selection it's important to first understand some of the terminology surrounding wheel design and fitment. Well cover some of the basics here but you are encouraged to seek other independent sources of information. As time passes some of the information will become dated but the basic concepts remain valid.
The quality of a wheel is a direct result of how it is manufactured. Consequently there is a direct relationship between price and quality. There are two principle methods employed to manufacture wheels: casting and forging. Aftermarket wheels include both cast and forged construction in sizes ranging from 16 to 19 inches in diameter. Some are anodized aluminium while others are painted and/or clear coated and even chrome plated.
One-Piece Cast Wheels
This is the most common type of aftermarket wheel. Casting is the process of pouring molten aluminium alloy into a mold where it cools and takes its shape.
Gravity casting is the most basic process of pouring molten aluminum into a mold utilizing the earths gravity to fill the mold. Gravity casting offers a very reasonable production cost and is a good method for casting designs that are more visually oriented or when reducing weight is not a primary concern. Since the process relies on gravity to fill the mold, the aluminum is not as densely packed in the mold as some other casting processes. Often gravity cast wheels will have a higher weight to achieve the required strength.
Low Pressure Casting
Low pressure casting uses positive pressure to move the molten aluminum into the mold quicker and achieve a finished product that has improved mechanical properties (more dense) over a gravity cast wheel. Low-pressure casting has a slightly higher production cost over gravity casting. Low pressure is the most common process approved for aluminum wheels sold to the O.E.M. market. Low-pressure cast wheels offer a good value for the aftermarket as well. Some companies offer wheels that are produced under a higher pressure in special casting equipment to create a wheel that is lighter and stronger than a wheel produced in low pressure. Once again in the quest for lighter weight, there is a higher cost associated with the process.
Rim Rolling or Spun-Rim
This specialized process begins with a low pressure type of casting and uses a special machine that spins the initial casting, heats the outer portion of the casting and then uses steel rollers pressed against the rim area to pull the rim to its final width and shape. The combination of the heat, pressure and spinning create a rim area with the strength similar to a forged wheel without the high cost of the forging. Some of the special wheels produced for the O.E.M. high performance or limited production vehicles utilize this type of technology resulting in a light and strong wheel at a reasonable cost.
The ultimate in one-piece wheels. Forging is the process of forcing a solid billet of aluminum between the forging dies under an extreme amount of pressure. This creates a finished product that is very dense, very strong and therefore can be very light. The costs of tooling, development, equipment, etc., make this type of wheel very exclusive and usually demand a high price in the aftermarket.
This type of wheel utilizes two or three components assembled together to produce a finished wheel. Multi-piece wheels can use many different methods of manufacturing. Centers can be cast in various methods or forged. The rim sections for 3-piece wheels are normally spun from disks of aluminum. Generally, spun rim sections offer the ability to custom-tailor wheels for special applications that would not be available otherwise. The rim sections are bolted to the center and normally a sealant is applied in or on the assembly area to seal the wheel. This type of 3-piece construction was originally developed for racing in the early 1970s and has been used on cars ever since. The 3-piece wheels are most popular in the 17 inch and larger diameters.
There are now many options for 2-piece wheels in the market. The 2-piece wheel design does not offer as wide a range of application that a 3-piece wheel allows, however they are more common in the market and the prices start well below the average 3-piece wheel. Some 2-piece wheels have the center bolted into a cast or cast/spun rim section and other manufacturers press centers into spun rim sections and weld the unit together.