Corvette D6C Forgeline Wheels - New Shoes

Quality
There are many reputable wheel companies producing wheels for the C6. But for every reputable company, there are a dozen marketing companies selling low-quality rims made god-knows-where. As with all other components you purchase for your car, it's caveat emptor when it comes to wheels.

So, how do you separate the good stuff from the crap? There are several features you should know about. First and foremost is the type of construction.

Cast vs. Forged
Alloy wheels are generally made in one of two methods: casting or forging. Almost all low- and midrange alloy wheels, including those originally installed on the C6, are produced by a manufacturing method known as casting. Casting involves flowing molten aluminum alloy into a mold, which then forms the wheel. There are actually several types of casting, each with its own advantages. The most common types are gravity casting and low-pressure casting.

Gravity casting is the simplest form of casting aluminum. Molten aluminum is simply poured into the mold and allowed to cool. This method is the cheapest way of casting aluminum and results in economical wheels that look OK but may not be as strong as those produced by more sophisticated means. The reason is that there are often small voids or air pockets in the casting. To overcome this limitation, the wheel must be made with thicker walls to compensate for the porosity, resulting in wheels that are heavier than those produced in higher-end processes.

In low-pressure casting, pressure is applied to the molten aluminum to improve its density. This allows a slightly thinner casting with more uniform density than gravity-cast wheels, resulting in less weight and an only slightly higher price tag. Most original-equipment wheels are produced in this way. There's also a variation that uses higher pressures to further enhance the benefits of this method. This is less common, as it increases costs.

Forging is the most advanced method of manufacturing wheels and also the most expensive. A forged wheel starts as solid billet aluminum that is forced between dies at very high pressure. In the case of the Forgelines we're featuring here, a 6,000-ton hydraulic press is utilized. As Forgeline's Scott Main explains, "Forging aligns the grain structure, improving the strength-to-weight ratio with consistent results. Forging also allows the use of 6061 material, which can be heat treated to be 40 percent stronger than cast aluminum."

As you might imagine, this creates an extremely dense structure with unsurpassed strength. Because of this, the wheel can be made thinner and lighter. Once the wheel center is forged into its general shape, it is CNC-machined to create the design style. Forging is clearly the best way to build a high-performance wheel, assuming cost is no object. It is on forged wheels that we will concentrate here.

Forged wheels are available in one-piece and multipiece varieties. Multipiece wheels are an excellent choice for several reasons. Three-piece wheels offer more flexibility in specifying offset (also known as backspacing) than a one- or two-piece wheel. This is because the center of the wheel can be adjusted to different thicknesses and then mixed and matched with different inner and outer rim halves to make virtually any combination desired. This also offers more flexibility in repair should the wheel become damaged. Rather than replacing an entire wheel, you can simply disassemble it and replace the damaged component.

This also benefits you if your fitment changes. For instance, say you decide to add a pair of Z06 quarter-panels to the rear of your C6. Rather than replace both rear wheels, your existing wheels can be rebuilt with different rim shells to achieve your desired fit. That's way better (and less costly) than replacing two perfectly good wheels.