There have been six generations of NASCAR Cup stock cars. In 2021, NASCAR unveiled its seventh evolution: the Next Gen race car. The association is testing the Next Gen car ahead of its introduction for the 2022 race season. Eagle-eyed fans noticed many changes, including the NASCAR Next Gen wheels’ distinct lack of lug nuts.
NASCAR Next Gen wheels have a single ‘mono lug’
Centerlock hubs are one of the oldest wheel styles. Early wire wheels consisted of spokes laced onto a splined center hub. This hub fit over a splined axle shaft and was held in place with a locking central nut.
Today, lug nuts have replaced centerlock hubs for most applications. But many autosports favor lightweight modern rims with centerlock hubs.
A centerlock wheel takes one-fifth as much time to unbolt as a five-lugnut-rim. As a result, centerlock wheels save valuable pit stop time. For this reason, Formula One and endurance Supercar racing leverage centerlock wheels.
Because centerlock rims are standard in racing events worldwide, many supercar manufacturers assemble their top-end street cars with centerlock rims. Several top trim Koenigseggs, and Lamborghinis and special Porsche 911s come from the factory with racing-inspired centerlock rims.
The NASCAR Next Gen cup cars will also utilize a centerlock hub and nut. NASCAR is calling its new system a “mono lug.”
Centerlock wheels have downsides
One downside of centerlock wheels is that their large hub nut must be torqued very tightly and takes a lot of force to loosen. But this is not an issue for a modern racing team equipped with impact wrenches.
Another downside of centerlock wheels is that they can fail catastrophically if not properly attached. During the 2021 Le Mans, a pit crew did not fully tighten a centerlock rim onto its axle splines. As a result, the Ferrari race car lost a wheel while on the track. In Formula One, a centerlock lug nut was even “stripped” by the pit crew, leaving Valteri Bottas’ Mercedes race car stranded.
The NASCAR Next Gen wheels are forged aluminum
NASCAR’s Next Gen cup cars will utilize centerlock hubs on their new, 18-inch aluminum rims. For six generations of new NASCAR Cup race cars, the Association has used steel rims. 2021 Cup cars used 15-inch steel rims. 2022’s Next Gen Cup cars will upgrade both the rim’s size and material.
The aluminum NASCAR Next Gen wheels will reduce the car’s unsprung mass. This means, these lightweight rims will maintain better traction across bumps or other road imperfections.
The forged aluminum wheels are closer to the rims on the production cars–the Camaro, Mustang, and Camry–that the NASCAR stock cars are supposed to represent. Many race fans may find the more modern rims just look better.
The end of NASCAR brake fade?
The new Next Gen NASCAR design increases the rim diameter to 18 inches. These larger NASCAR Next Gen wheels will offer several benefits.
The combination of larger rims and the smaller centerlock hubs means new NASCAR Cup cars will have room for much larger brakes.
Chad Knaus is a seven-time NASCAR-Cup-winning crew chief and current Vice President of Hendrick Motorsports. Knaus calls the new brake system “really great.” He says the significantly larger rotors allow “the driver to get the car slowed down without generating a lot of heat.” Overall, NASCAR predicts 25% more stopping power for the large Next Gen brakes.
In addition to the larger brake rotors, the aluminum material of the new rims will expel the brake heat much faster. The new wheel design also offers a lot of open area for quicker brake cooling. This new rim and brake package may put an end to the dreaded NASCAR brake fade drivers experience during long races.