NASCAR switching to single lug nut design for 2021

Beginning in 2021, NASCAR Cup Series teams will work with a single, center-locking lug nut on its race cars.

The move was confirmed Monday as William Byron tested the phase 3 prototype of the Next Gen race car at Fontana. Byron was driving a car that featured the single lug nut.

"One of our main goals with the Next Gen car is to provide a vehicle that better replicates what our OEM partners sell in the showroom – both in looks and relevant technology," said John Probst, NASCAR senior vice president of racing innovations. "Moving to an 18-inch forged aluminum wheel helps do just that.

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"Once the decision was made to go that direction, we tested different lug nut options. With the loads on the larger wheels, we had to make sure that the wheel would remain securely fastened to the car. The single lug, center-lock design was the best way to accomplish this."

Next Gen is slated to debut next season. In addition to the sport moving away from using five lug nuts on its tires, the tires themselves will increase in size from 15 inches to 18 inches.

Probst said the choreography of a pit stop will not change with a single lug nut. Teams will still have the same over-the-wall crew, and the same rules for pit road will be in effect.

"It will still be important for the tire changers to be quick off the wall to get to the far side of the car," said Probst. "Hand-eye coordination remains extremely important; you're still trying to get the lug and tire on and off the car faster than 39 other teams. The overall way a pit stop looks will remain the same.

"In terms of timing, the torque is higher on the single lug, which means they have to leave the gun on longer. In our testing, we've found that it takes approximately half a second to properly tighten this new lug. Today, a good tire changer can remove five lugs in about 0.8 seconds. So, while pit stops may be a touch quicker next year, it won't be a significant difference."

Auto Club is the fourth test for Next Gen, and the largest facility that the car has been to.