Steve Letarte breaks down how cars are built for the high-stakes NASCAR Cup Series playoff race at Charlotte Roval

The NASCAR Cup Series Playoffs reach their second cut-off race this weekend at the Charlotte Motor Speedway Roval. Four drivers will see their championship hopes end when the checkered flag falls on the Bank of America ROVAL 400, a race that has built its reputation on unpredictability.

At stake are six open playoff spots. With Chase Elliott and Ryan Blaney already qualified, a good or bad day at the Roval can swing the entire playoff picture. The 2.28-mile Roval course demands a strategy distinct from most road courses, with infield corners, oval speed, and heavy braking zones.

Ahead of the race, former Hendrick Motorsports crew chief Steve Letarte explained how teams approach the unique car setups for NASCAR’s most unusual road course.

"The aero setup is much like we see at the short tracks and that starts with that simple diffuser underneath the race car. There’s not a lot to it. It’s a lot shorter than what we see at the intermediate tracks. Less vertical fencing and for that reason creates less downforce, let more instability under braking," Letarte said (via NASCAR).

A taller diffuser typically creates more under-car downforce, improving grip. The Roval’s shorter diffuser does the opposite, reducing stability under braking and in tight chicanes. That puts added importance on the front splitter - a flat lip at the nose of the car. NASCAR Cup Series teams use 'stuffers' to fine-tune airflow, balancing drag and downforce.

The 2025 NASCAR Cup Series Enjoy Illinois 300 at World Wide Technologies Raceway. Source: Getty

At Charlotte, front downforce is critical. Reducing too much of the same puts the Next Gen car at risk of locking the front tires or understeering into the corner entries. Letarte added another key difference between road courses and short tracks is preparation for wet weather.

"This is where short tracks and road courses split. Because in the road courses, we will run not just on wet tracks, but in the rain. For that reason, we have rain flaps to try to keep the spray down, coming off the rear tires. Trying to help with visibility. That could be a big challenge, especially the high-speed sections, that backstretch on the Roval or heading into the front stretch chicane," he added (0:42 onwards).

Those flaps break up the rooster tails created by water off the rear tires, giving trailing drivers a better view. Other details that come into play are the single window rail to reduce drag while keeping side windows sealed, a compact 3-inch spoiler, and a mechanical windshield wiper in case of heavy rain.

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Tires will be key in the NASCAR Cup Series Bank of America ROVAL 400

Goodyear Eagles racing tires for the NASCAR Cup Series race at Dover Motor Speedway. Source: Imagn

Sunday’s 109-lap Bank of America ROVAL 400 is the final chance for drivers on the bubble to survive the Round of 12. The margin is razor-thin with the last six drivers in the standings separated by just 69 points. Ross Chastain, Bubba Wallace, Tyler Reddick, and Austin Cindric are currently on the outside looking in.

What won’t be a mystery is the tire setup. All three national series will run the same Goodyear Racing Eagle road course tire that has already been used at COTA, Mexico City, Chicago, Sonoma, and Watkins Glen this season.

"The Charlotte road course combines tight chicanes, a slower infield section and much of the track’s oval, making for a unique combination... We’ve introduced new Goodyear Racing Eagle tire setups for all three series earlier this year, so we expect teams to be comfortable with their setups by now," said Rick Heinrich, Goodyear NASCAR product manager.

Teams will also have wet-weather tires ready, easily identified by white Goodyear lettering, in case of rain. The extra grip and tread pattern give drivers a fighting chance in conditions where visibility and handling are already difficult.

Connor Zilisch and NASCAR Cup Series driver Shane Van Gisbergen at Sonoma. Source: Getty

Shane van Gisbergen has won four straight road course races and carries a career win percentage of 45% on road courses, best in NASCAR Cup Series history. He’ll be the favorite again. In the Xfinity Series, 19-year-old Connor Zilisch enters on pole on Saturday, with just 30 points separating the last eight drivers in another close elimination battle.