Wheels and tires are one of the first modifications track-car builders reach for, and for good reason. However, picking the proper wheel and tire package for your performance build can be a tricky proposition of balancing performance and aesthetics. Left to off-the-shelf selections, finding a perfect fitment solution to your rolling stock needs is an unavoidable game of compromise; especially for a car that will see both track and street time. Let’s see if we can turn some of those compromises into purpose-built solutions, advancing our project a little closer towards the perfect package.
Project Lucky 13, our 2013 theft-recovery Camaro SS, lost its factory wheels and tires to thieves, but no matter because this car is destined for much more action than GM intended. Our Camaro is going to be a driver, a car that passes California smog laws and can be daily driven; but is ready to tear it up at the track at a moments notice.
The benefits in weight, grip, and fitment (with larger brakes) make new shoes a rational modification. As is recognized everywhere, the first few seconds shaved off your lap time are the simplest, and often cheapest. Good racing tires, even DOT-approved ones, can take a bigger chunk of time off your sessions than nearly any other modification.
Forgeline Motorsports produces industry benchmark-setting rollers, born from racing and tailored to aftermarket applications. We chose to equip our Camaro with wheels from one of its long-lived and proven designs, the GA3R. Wrapping up all of that milled aluminum are Toyo Proxes R888 tires, ensuring we have the multi-weather adhesion to keep our fifth-gen planted on the tarmac.
Forgeline GA3R: Engineered For Enthusiastic Driving
The wheels for this project had to be something special, a track-bred and engineered package that would hold up to the rigors of enthusiastic driving, but also offer the peace of mind we demand for the thousands of miles driven on the street. Forged wheels are unparalleled in its class, and recent advances in design and testing software have allowed more weight to be shed and strength gained. Forgeline has been in the wheel game for decades and its proven track record is credential enough to convince us, but its data can also back up the claims. We chose the 19-inch diameter, 10.5-inch wide, GA3R for our application.
“The GA3R was developed for professional road racing, so we focused on making a wheel that would clear large brake calipers, have low deflection, and high strength. Aesthetics didn’t matter, the wheel was functional and that’s what was important,” explained Steve Schardt of Forgeline. “Our engineers kept testing and testing, and this was the design that kept coming in. It has some limitations … it can’t be a four-lug, for example. As tires have gotten grippier, some radiuses needed to be changed by identifying what was flexing and either beef it up or shot-peen the surface.”
Wheels are often overlooked as a fatigue item, which is a dangerous mistake to make. Like nuts, the bolts, axles, spindles, gears, and engines, wheels are a stressed member of any racecar platform. The miles and hours of load a car experiences work-hardens and stresses metal, and no wheel is immune to that. Forgeline recognizes this inevitability and accounts for it in its designs.
“Forged wheels are pretty bulletproof, but it is still eventually a fatigue item. When designing a wheel you have to look at it from three perspectives; life, strength, and weight. Of those three, you can pick two,” says Schardt. “So, you get a wheel that isn’t ultra-light, but still very lightweight while using titanium hardware and is very strong. Racing wheel designers don’t look at wheel life in years, but rather track time.”
How wheels take their shape is determined by the motivations of the manufacturer. While aesthetics may drive most of the aftermarket trends, the engineers at Forgeline are focused on performance. The GA3R includes a number of features that are easily overlooked, but still important to the final product. Among these are I-beam spokes, hidden hardware, and a stepped lip design.
“What’s funny is that you’ll see I-beam spokes on a lot of other wheels now. This beam design gives you the strength and load deflection required of a wheel, while also saving weight.” Schardt explains. “When we started developing the I-beams, our machinist would take out a whole bunch of material and then look at the properties and add some material back in as needed. We have reached a point now where the I-beam is just as strong without the extra material as it is with it.”
Moving on to the hardware, Schardt continues his explanation. “The nice thing about using hidden hardware is that the wheel is easier to put together and take apart, you don’t have another nut to hold on to during assembly. During production helicoil’s (helical thread insert) are added so that you’re not threading titanium fasteners into aluminum. There is a total of 40 M8 bolts used on the GA3R so that the customer can repair the wheel using the existing bolts, compared to M6 hardware, which has to be replaced every time you take it apart.”
The GA3R is a three-piece design wheel, meaning that the barrel is a two-piece design supported by a one-piece center. This architecture spawned out of a movement for modularity, ease of repair, and cost of manufacturing. By machining the individual components of the wheel out of separate forgings the costs of the respective materials drop; interchangeability for size, color, and offset become options; and repairs of individual damaged pieces can be completed track-side.
“When Forgeline would go down to a 24-hour race, we’d take a van and be working pretty much all night, depending on what would happen on the track. If a race team needed a wheel to be repaired — you couldn’t do that with a one-piece,” Schardt recalls. Some of it’s for looks, too, … a lot of guys like to change colors between the center and outer.”
Manufacturing A Racing Wheel
Material is removed on the CNC mill to shape the spokes.
Turning a raw billet or aluminum forging into a Forgeline wheel isn’t as simple as pushing “go” on the CNC machine. The work starts as soon as the engineers concoct a design to suit the demands of the modern racer, which involves extensive computer modeling and testing.
“We have our own Finite Element Analysis (FEA) program; we can make something using our own calculations from the data the FEA has accumulated over 20 years of racing,” Schardt proudly explains. “After that, every wheel is destructive-tested, both static and dynamically. We put a huge load on the wheel and then rotate it, trying to make the wheel fail. We normally look at 200,000 test cycles … this means that our wheels would exceed TUV standards.”
Once any problem areas have been identified and overcome, thanks to FEA, the wheel can actually go into production. A 6061-T6 aluminum forging is turned in a CNC lathe in two operations to complete machining on both sides before proceeding to the mill. The center spoke designs are carved out of the forging and the holes for lug studs are bored. A final facing pass cleans the backside and so ends the machining. The human touch is important to Forgeline because a machine just can’t deliver the finish quality demanded.
Finite Element Analysis digitally subjects a modeled part to a load and reveals stress areas. Hot spots indicate potential problem areas.
“It then goes to the grinding room where every center is hand-ground because you don’t want any machining marks or burrs on the finished product,” Schardt states. “There isn’t really a better way to do it than by hand. After the grinding room, the GA3R is then shot-peened, media blasted, and finally powder-coated.”
Forgeline wheels are powder-coated in the last phase of production.
The barrels of the wheels are manufactured in a slightly different fashion. Using a rotary forging procedure, they are spun and heat-treated to the desired final temper. “The barrels are a different alloy because it’s difficult to use 6061-T6 in a barrel. There are only a few companies using this alloy, most use a softer 5,000 series because it’s much easier to work with,” Schardt explains. “The barrel is spun into a shape, and this gets it to about a T5 state. Once it’s worked, it goes to heat-treat and this puts it at T6.”
Tailoring Individual Wheen Packages
Forgeline has the ability to take a customer’s application, and specific goals, and then tailor a wheel package that will best suit them in the long run. Expect a barrage of questions, all in an effort to make sure your ride is equipped with the best Forgeline can recommend.
“The first question is track or street, the next question is how close do you want it to the fender? Aggressive or something nice and stock, are you going to lower the car? What brand of tires are you looking at, because that can also change the size of the wheel. Once we get a feel for where the customer wants to go, it becomes a lot easier,” Schardt relayed.
For our Camaro, we knew we wanted a meaty setup, something that would make the best use of the car’s updated suspension design. A “square setup,” that is, wheels and tires of the same dimension on all four corners, would be the selection of choice, and clearly announces our intentions as track-focused. This school of thought moves away from the conventional staggered wheel sizing and section width that is common on many cars. By making the contact patch symmetrical front-to-rear, side-to-side, and diagonally, we distribute traction much like corner balancing.
“We like using a square setup, it does a lot more for you. It balances the car very nicely and you can rotate tires from front-to-rear and side-to-side, we do that with a lot of cars. There are quite a few cars out there that can benefit greatly by using a square set-up, especially if you are going to a driver’s school or just having fun at an open track day,” Schardt explained. “Cars are generally designed to push and understeer, so unless you have gobs of horsepower and you want a little bit more rubber in the rear, putting just a wider rear tire on the car will make it worse.”
One of the biggest mistakes that comes back to bite wheel buyers is pairing a racing tire with a wheel rated for street loads. The enhanced grip a racing tire provides a car translates to higher loads transmitted through the wheel. Many buyers overlook this important consideration, and subsequently break wheels prematurely.
A load rating sticker inside the bead gives users an idea of what they can expect with different treadwear tires.
“That’s the biggest thing that most people don’t understand — the load rating of these wheels, and why that’s so important. The GA3R has a load rating of 2,100 pounds, and that’s great because the Camaro doesn’t weigh 8,000 pounds, or have 4,000 pounds in the front,” stated Schardt. “When you start adding more tire, stickier compounds, and aerodynamics it starts slashing the load rating down due to the increased stresses.Using the Toyo Proxes R888, which has a treadwear rating of 100, will probably cut the max load of the wheel by about 35 percent,” Schardt cautioned.
“Say you find a wheel with a load rating of 1,500 pounds … if you slash that by 35 percent, you’re down to 1,000 pounds per wheel, and now you’re starting to worry about the front,” he continued. “You’ll notice that some wheels are breaking the centers out, this is a fairly common occurrence when putting a racing tire on a wheel that has a street load rating.”
“Using the Toyo Proxes R888, which has a treadwear rating of 100, will probably cut the max load of the wheel by about 35 percent,” Schardt cautioned. “Say you find a wheel with a load rating of 1,500 pounds … if you slash that by 35 percent, you’re down to 1,000 pounds per wheel, and now you’re starting to worry about the front. You’ll notice that some wheels are breaking the centers out, this is a fairly common occurrence when putting a racing tire on a wheel that has a street load rating.”
By selecting a wheel that most certainly exceeds the capacities we will subject this car to, we can rest assured that they will serve us safely for years to come.
Toyo Proxes R888 For Performance Traction
For dry and wet performance traction we turned to the DOT-approved R-compound Toyo Proxes R888. These 100 treadwear rated tires feature unique construction cues to enhance handling characteristics. As competition-bred tires designed to be at home on the racetrack, they also still spirit you to and from your track day on the road.
The tread design uses a V-shaped siping pattern engineered to shed water, a continuous contact patch center for enhanced braking, and a semi-slick shoulder for enhanced grip at maximum cornering g’s. The sidewall features a stiffer bead design, steel wire-reinforced structure to resist tire deflection under heavy side loads, and a spiral-wound cap to help maintain uniformity at varying speeds.
The tread design can be shaved for shallower depth and increased grip under dry conditions, but the operating temperature remains a moderate 160 to 220 degrees F. The R888 performs best with maximized positive caster and between one and three degrees of negative camber. We decided to use 305/30R19 tires on all four corners in order to maximize the contact patch and balance front-to-rear traction.
“We developed the Proxes R888 100-treadwear DOT competition tire to have an optimized casing and tread design to maximize dry performance without losing wet traction. It has been designed for use in road racing, track days, and high-performance driving schools,” explained Drew Dayton of Toyo Tires.
The Proxes R888 will definitely suit the multipurpose nature of Project Lucky 13. The theme for this build is a Camaro getting a second chance at life and these new shoes will certainly set it off on the right foot. Stay tuned for track testing impressions and maybe few more aggressive body lines.