How They’re Made: Forgeline Motorsports Wheels

For over 20 years Forgeline has made a name for themselves in both racing and street wheels. Some of the biggest names in road racing as well as many well known pro-touring shops use Forgeline. Both our Project Swinger Nova, and more recently our Blank Slate ’69 Camaro are running these wheels. A while back we gave you a look at the custom wheel features of the Forgeline SC3C wheels we had built for Blank Slate. This is one of Forgeline’s wheels, aimed squarely at the street market.

We custom ordered these Forgeline SC3C wheels for our project Blank Slate ’69 Camaro – check out what it takes to build a high quality wheel from scratch.

Forgeline engineers their designs based on the company’s vast racing experience and understanding of wheel engineering. “Most of our hard work is done in the design phase,” says Forgeline’s Steve Schardt.

Taking Measurements

The main thing is getting the machining right, and the engineering right before a wheel is ever cut. -Steve Schardt

If the customer’s car is mostly stock, then chances are a representative from Forgeline will have information available to select the proper measurements for that car. However, many of Forgeline’s customers are building or driving heavily modified cars. Changes to the car’s suspension, body, frame, and braking system, can drastically affect the wheel fitment. This means measuring for the new wheels is an area requiring precise attention to detail.

To aide their customers, Forgeline has a detailed chart on their web site that shows what specific measurements are needed to build a custom wheel. The measurements are critical for both the front and rear wheels.

The six measurements needed for proper custom fit are: 1 Front Spacing, 2 Rear Spacing, 3 Caliper Clearance, 4 Caliper Height, 5 Hub Diameter, 6 Hub Height.

Dimension 1: Front Spacing. This is the distance from the hub face of the rotor to the fender lip or other  other outer interference area.

Dimension 2: Rear Spacing of the Wheel. The distance from the hub face of the brake rotor to the inner fender.

Dimension 3: Horizontal Caliper Clearance. This is the distance from the face of the outside face of the caliper to the hub face of the rotor.

Dimension 4: Caliper Height. This is a measurement of the distance from the center of the hub to the highest point on the top of the caliper.

Dimension 5: Hub Diameter. The portion of the hub that sticks through the rotor is the next dimension. This measurement is critical to ensure you get the proper diameter hub hole in your wheel center.

Dimension 6: Hub Height. The final dimension needed, this is how far the hub protrudes above the rotor face.

Starting With CAD

All designs from Forgeline begin in CAD software. The software combined with real world testing data is used to analyze designs for stress or weaknesses. These issues can be fixed using the company’s experience in engineering wheels. Things like I-beamed spokes help make sure the wheel design is strong, while maintaining light weight. “The main thing is getting the machining right, and the engineering right before a wheel is ever cut,” says Schardt.

Once a wheel center design is rendered in CAD, software then determines stressed or weaknesses in the design. Forgeline can then make changes to the design to resolve these problems before building the wheel.

While their existing designs range in availability from 17-22 inch diameters, with up to 16 inches in width, Schardt tells us, “There haven’t been many wheels that we weren’t able to make.” This type of capability, combined with their dedication to customer service has allowed Forgeline to move from their roots of building strong and lightweight racing wheels, into the street, and Pro-Touring market. “Most of the racers who have our wheels on their track cars, also have them on their street cars,” says Schardt.

Building a Wheel

Since Forgeline builds their wheels from a billet, not a casting or stamping, the build process is different than that of many other wheels.

From a Blank

The center of the wheel is the foundation of any wheel. Once a design is chosen, Forgeline begins the process of building the wheels using a blank piece of 6061 T6 billet aluminum forging. This billet is forged using a 6,000 ton press, which aligns the grain structure for maximum strength.

After the back of the wheel center is cut on a lathe (left), it is then put into the 4-axis CNC mill where it takes shape (right)

To begin building a wheel, the wheel center blanks are loaded onto a lathe. The lathe cuts the top and bottom faces of the wheel center. This gets the correct diameter and profile for the center.


Once the wheel has taken shape on the lathe it is then moved to a 4-axis CNC mill. This is where the center of the wheel starts to become recognizable. The CNC mill first cuts the wheel spokes and design out. For our SC3C wheels it then cuts the centers of the spokes, followed by the chamfers. From there the wheel bolt pattern is drilled, followed by the assembly bolt holes. Last, the machine mills the pad for the proper offset of the wheel being built.

As the CNC mill cuts away at the blank, our SC3C wheel center starts to take on a recognizable form.


After milling, all wheel centers are sent to the polishing room for inspection. Centers are checked here for any machining lines present after the milling process. Any such marks must be carefully ground out by hand.

If a wheel center is getting a polished finish it will stay in the polishing room and undergo a multi-step process to bring it to a mirror shine. If it’s getting painted or coated it will be sent to the appropriate area after inspection.

Left: you can see the mounting pad of our wheel center. Right: The wheel center face has all the machine work finished including cutting the split spokes, chamfers and drilling the hardware hole.

Finish and Options

Forgeline offers a wide array of finishing options for their customers. These options range from the basics that have been around for years, such as polishing, painting, plaiting, powder coating, and anodizing, to more exotic options. Customers can select custom paint colors, to match or contrast with their car. Centers can have a colored accent put in them, as well as race gold finish. For our SC3C wheels we chose transparent smoke. A transparent copper finish is also one of the new options. Centers can also be fully brushed. Inner and outer shells can be painted, polished, brushed, or powder coated as well, giving virtually endless possibilities.

There are hardware options to select as well. Customers can choose to have the hardware visible or hidden. Visible hardware is cool in some applications and gives the wheel a mechanical, almost European feel. Hidden hardware seems to be more that classic American smooth style. The visibility of hardware is simply a matter of customer preference.

Customers can select from either 12-point or piston head stainless fasteners, or lightweight titanium fasteners. The nuts used to secure the hardware can also either be standard ARP, or chrome-moly jet nuts, both are lightweight and strong. Using high quality hardware means that should the wheel ever need to be serviced, it can be done without requiring the fasteners to be discarded once removed.

We chose to use the standard ARP stainless fasteners for our wheels. We also chose to have them hidden, which will give our wheel a smooth, classic appearance.


The next step is assembling the wheels. Forgeline wheels off 3-piece designs; in this step all three pieces -the inner, outer, and center, finally come together. The inner and outer sections come from one of two sources, they are either manufactured in house by Forgeline, or are sourced from their supplier in California. Regardless the final finishing and machining of all parts of the wheel are done in house at the company’s Dayton, Ohio facility, and the wheels are assembled with the hardware specified in the order.

The next step in assembly is to seal the wheels. Unlike a cast wheel, a 3-piece wheel must be sealed where the components meet to ensure that it will hold air once the tire is seated on it. After years of testing, Forgeline uses a sealant sourced from Loc-Tite to seal all their wheels. Good sealant isn’t the only key to no leaks, “The aluminum has to be prepped correctly,” says Schardt.

Left: A sealant is applied to the wheels where the sections meet to prevent leaks. Right: A dial caliper is used during the inspection process to check run out.


With the wheels assembled, they’re now ready to make their way to the final inspection room . Here, each wheel is carefully checked by hand for any flaws or imperfections.

Wheels need to be round, so run out is also checked closely. Too much run out, and even a properly balanced wheel will cause vibration issues. The wheel industry generally has a run out tolerance of .030 of an inch. Forgeline goes a little further and uses a tolerance of .020 of an inch for all the wheels they manufacture.

Once a wheel has passed final inspection and cleaning, it is boxed and shipped to the customer. It usually takes three to four weeks for most street car orders to be completed and shipped.

Left: We love the deep lip of our front and rear wheels. It gives the concave design that much more of a muscle car feel. Center Left: We chose trasparent smoke finish for our spokes, with a brushed lip, this gives the wheel a modern Pro-Touring look. Center Right: The mounting pad is built to our specs, no spacers are required to make these wheels fit our car since they were built to our exacting specifications. Right: This yellow label contains the load information for the wheel, it is important that the load not be exceeded.


40 Fasteners

The three wheel sections are held together by 40 fasteners. That number remains the same regardless of the wheel diameter. Forgeline has found that this gives the best level of strength possible to their wheels while still maintaining lightweight. Each fastener is put in by hand, then torqued by hand to 25 lb-ft. This ensures that every wheel is safe, strong and true.

This is an area where customers must be extremely cautious. When receiving a set of wheels, before mounting the tires a complete inspection should be performed. Forgeline advises that all lug nuts get checked to make sure they are the correct thread pitch, diameter, style, and length for the application. Check all of the wheels, make sure that each wheel is what was ordered and wasn’t damaged in shipping. Make sure the bolt pattern is correct. Wheels should then be test fitted to ensure proper clearance. Once proper fit and clearance are verified tires can then be mounted.

Tires should be mounted by a trained professional, familiar with 3-piece wheels. Special care must be taken to avoid damaging the wheels, especially the sealant. Also, new valve stems should be used whenever a tire is replaced. Forgeline offers many tire packages with their wheels, and will have them professionally mounted and balanced prior to delivery to the customer if they’d prefer.

When installing on the vehicle, use only wheel nuts or bolts supplied by Forgeline. Also be sure to torque the wheels to your manufacturer’s specification. Forgeline recommends hand torquing, if an impact gun is used, wheels should first be tightened on a lower setting before final torquing.

Like any automotive product you definitely get what you pay for. Forgeline offers their customers wheels that are not only built to higher standards than the wheel industry norms, they also offer the highest levels of product engineering, personalization, quality control, and customer service. This ensures the wheels that are ordered are as unique as the car and owner who use them.

Chevy Hardcore project car “Blank Slate,” a vintage ’69 Camaro destined for the Pro-Touring and Autocross circuits, recently upgraded with a set of Forgeline wheels. Follow the project car build thread on “Blank Slate” by clicking here.

About the author

Don Creason

Don Creason is an automotive journalist with passions that lie from everything classic, all the way to modern muscle. Experienced tech writer, and all around car aficionado, Don's love for both cars and writing makes him the perfect addition to the Power Automedia team of experts.
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