NASCAR Sprint Cup Series, Race No. 16 – Toyota / SaveMart 350
Hard on Brakes + Hard on Throttle = Hard on Tires at Sonoma:
Going from slow speed corners and back hard to the throttle will create difficult handling conditions for Monster Energy NASCAR Cup cars at Sonoma Raceway this weekend. That deceleration and acceleration is also a challenge for Goodyear as such harsh changes puts an increased stress on the front tires with heavy braking into the turns and an increased stress on the rear tires with harsh acceleration off the corners. Those factors combine to put undue stress on the tread splice, the area of the tread that is joined together in the manufacturing process. Because of all that, Goodyear will mount its D-4678 tires (same on all four corners of the car) for Sonoma in a directional manner, helping to insure that the tread splice is “closed” under both braking and acceleration.
“For Sonoma, we will employ directional mounting, where the left-front and right-rear tires are mounted the same, and the right-front and left-rear are mounted the same,” said Greg Stucker, Goodyear’s director of racing. “This directional mounting helps to protect the beveled splice of the tread component, insuring the splice is closed under the force of braking on both front tires, and closed under the force of acceleration on both rears.”
While helping the competition on the track, this mounting procedure will provide a slightly different look for team tire specialists as they arrange their tire sets this weekend.
“The right-front tire and the left-rear tire will be mounted with the ‘non-serial’ side facing outwards,” said Stucker. “The molded information for press position and date code on these tires will be on the inside of the assembly rather than the outside. During mounting, the tires will be marked with the positions in which they are allowed to be run – right-front/left-rear or left-front/right-rear. This will allow both tires on the front axle to have tread splices that close under braking and both tires on the rear axle to have tread splices that close under acceleration.”
To go along with all that, Goodyear’s distinctive yellow lettering will be applied to both sidewalls of each tire. That way, no matter which side of the car a particular tire is mounted, the “Goodyear” and “Eagle” branding will be visible.
Teams in the NASCAR Sprint Cup Series will run the same Goodyear tire code (D-4678) on all four tire positions at Sonoma. This tire debuted at Sonoma in 2016 and is the only track at which teams in NASCAR’s three national touring series will run this tire code.
On all NASCAR road courses, teams will not run inner liners in their tires at Sonoma.
Wet Weather Tires:
Goodyear will bring its wet weather radials (D-4215) for use at Sonoma, should NASCAR decide that conditions warrant. Teams are allowed up to three sets of "wets" for practice/qualifying and up to three sets for the race. This tire code was last run by NASCAR Xfinity Series teams at Mid-Ohio last season.