BRISTOL, Tenn.—Goodyear, in partnership with NASCAR, is planning to change the design of the race tires it supplies to the NASCAR Cup Series to a larger rim diameter, perhaps 18 inches versus the current 15-inch formula, by 2021.
The change would coincide with the introduction of NASCAR's "Generation-7" vehicle design, scheduled to debut in the 2021 season.
The change would help make the cars on the race track more closely resemble their street counterparts, nearly all of which are now fitted OE with larger-diameter tires, according to Greg Stucker, director of racing for Goodyear.
It's far too early now to discuss how the change would affect on-track performance, Stucker said in an interview posted on nascar.com.
The change initially would affect just the Monster Energy Series cars, Stucker said.
The Gen-7 vehicle/engine design concept is NASCAR's proposed formula to replace the chassis/engine package in place since 2013 and is designed to help attract vehicle brands other than Chevrolet, Ford or Toyota—NASCAR's current stable of manufacturers—to compete.
One of the biggest changes on tap for the Gen-7 design would be a switch to bodies constructed from a flange-fit composite material instead of steel, John Probst, NASCAR's vice president of innovation and racing development, told the motorsports media earlier this year.
The Gen-7 body/chassis change is slated to become effective in 2021, while a new engine rules package more likely will debut in 2022.
NASCAR is also expected to maintain a "common template" style body while providing room for each participating vehicle brand to be distinctive.
Goodyear, NASCAR's exclusive race tire supplier since 1997, renewed its supply contract with the race-sanctioning body in 2017 for an undisclosed number of years.