18-Inch Centerlock Wheels Coming With Next Gen NASCAR Racer

NASCAR Cup Series Next Gen Goes To Center-Lock Wheels
Just one of numerous changes for 2021
(CONCORD, NC – MAR 5, 2020 – RIS) The Next Gen's fourth on-track test, scheduled this week at Auto Club Speedway saw NASCAR's 'Next Gen' car tested by William Byron on the new design's . The three previous tests featured a larger aluminum wheel, but with the five-lug pattern that's been used in NASCAR for decades.

NASCAR's Senior Vice President of Innovation and Racing Development John Probst said the move away from a 15-inch steel wheel is part of a move to try to provide more relevance and closer relations to today's production cars with an 18-inch wheel, but that a strong enough fastener that could hold up under high-speed conditions was a necessity.

"For us we felt like from a standpoint of the wheel is that we wanted to get to an 18-inch wheel, an aluminum wheel," Probst said. "Once you get to an 18-inch aluminum wheel, the next step for us is to make sure that from a durability standpoint under racing conditions is that it will accept the durability that we need to finish races and then also finish multiple races. To do that, the single nut was our only option."

William Byron was the driver for this week's test of a new Next Gen prototype on the 2-mile California oval. Like earlier tests, the wheels used in Next Gen testing were made by BBS. BBS is a German company with American headquarters adjacent to Road Atlanta in Braselton, Georgia. BBS has a long history in racing, most notably in sports-car racing.

The single-lug wheel will be a departure for NASCAR, but other changes will be more subtle. Probst says that competition officials do not expect major changes to of pit stop execution, the five-person limit on crew members who go over the wall or team rosters overall.

"I think from a fan standpoint, the choreography of the pit stop will look unchanged," said Probst. "I think that a lot of times when we say single lug nut, people fear that it's an open-wheel style pit stop where people will be on their knees waiting for the car to come in. We don't intend to change anything with respect to how the pit-stop flow is executed.

"There will still be guys coming off the wall, there will still be a premium for that athlete to come off the wall, get to the right side of the car, make that tire change, get over to the left side of the car and make the tire change. From the look and feel of the pit stop, we don't see any significant changes."

While over-the-wall crew and their actions will stay generally the same, other changes will affect pit stops. Because the new, larger single lug will require more torque to properly fasten the wheel, the average pit stop time will not change appreciably, according to Probst.

"On the on and off, they still have to keep the gun on — they can't just cap it, it's got to actually ratchet a few times before it actually gets tight," Probst said. "So today, good tire changers can take five lug nuts off or put them on in less than a second, say eight-tenths of a second to a second. They're going to have to leave the gun on for probably at least a half a second, so if anything, they may be three-tenths (quicker) here and there, but it shouldn't dramatically change the timing on the pit stop."

The torque is especially critical, with just one contact point for the wheel. With the current five-lug system, the chance that one or more of nut isn't fully tightened in race conditions is higher.

"The steel wheel is more forgiving and can handle loose wheels a little bit better," Probst said. "When we get to the aluminum wheel, we did some durability studies and if you leave lug nuts loose on an aluminum wheel, you reduce the durability of the wheel by around 30%. It's more of, the aluminum wheel has less tolerance to loose lug nuts, so when we have one, there really is only one thing to concentrate on, and that is to get that lug nut tight. Then everything else from a durability standpoint is fine."

Another subtle change is coming in pre-race routines: teams normally glue lug nuts onto their allotment of tires before the race, speeding up replacement during stops. The single-lug system seems to eliminate that chore in the Cup Series next season.

"One of the things when you look at the single nut, it actually is retained in the socket, so they'll actually use the same single wheel nut for the entire race and likely multiple races," Probst said. "They'll use the same lug the entire time, so the concept of gluing lug nuts to tires goes away, which creates some efficiencies for us. There's times when we have to open up the garage or pit road early on race day for no other reason than for the race teams to glue up 11 sets of tires. They can just use the wheels as they are without being glued."

In actuality, the single center-lock wheel nut is only a minor change compared to some others: the cars racing in the NASCAR Cup Series for 2021 will have:
Larger brakes to take advantage of the larger 18-inch diameter wheels;
Independent rear suspension;
Composite bodies instead of the current steel bodies;
Sequential shift gearbox.
Of course, there are other changes, but few of them will be visible from trackside and some have even been made with a view toward servicing, such as widening the front clip to allow easier removal and replacement of valve covers in the garage.

John Davison

Long-time RIS staffer, beginning in the mid-80s. Charlotte, NC area local contact.

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Volume 2020, Issue 3, Posted 4:48 PM, 03.05.2020