Bias ply tires return to Cup Series for Bristol Dirt Race

In 1989, Goodyear began transitioning from bias play to radial tires in NASCAR competition. None of the current Cup Series drivers have run a bias ply tire in a Cup series race previously.

Because of the dirt track configuration for this weekend’s race at Bristol (Tenn.) Motor Speedway, teams will be running two new Goodyear tire codes this weekend.

While the tires feature the same block-style tread pattern that the Trucks ran at Eldora Speedway as recently as 2019, both the left-side and right-side tire feature construction changes compared to those tire codes.

Bias ply tire for Cup Series dirt race at Bristol

Photo by: NASCAR Media

“Bias ply tires are much more compliant than radials because they don’t have a belt package under the tread, making it more able to conform to an uneven dirt surface,” said Greg Stucker, Goodyear’s director of racing.

“The other obvious difference between these tires and the ones teams run on Bristol’s concrete surface is the presence of a tread pattern. All of our tires have a tread, but the concrete and asphalt tires do not have a tread pattern.

“These dirt tires have a block-shaped pattern, both to bite into the dirt and evacuate it so the cars have grip.”

The size of the left-side tire also has some differences. The left-side tire is significantly shorter than usual to build in more stagger between the left- and right-side tires.

The tire is based on a dirt modified tire in Goodyear Racing’s tire line, though it has been widened out to 11 inches (from 10 inches on the dirt modified tire) to give the NASCAR cars and trucks more grip.

Cup teams will receive three sets of tires for practice, one set for their qualifying heat race and five sets for the race (four race sets plus one transferred from qualifying).