NASCAR’s West Coast Swing ends this weekend at Auto Club Speedway in Fontana, California. The 2-mile speedway is only the second track larger than 1.54-miles that NASCAR has visited so far this season.
NASCAR Cup and Xfinity Series teams will use the same tire combination this weekend. The combination is unique in its use for Auto Club Speedway. Xfinity teams will have a different minimum recommended inflation on their left-front tires.
Cup team will be allowed four sets for practice, one set for qualifying/start of race and 10 sets for race. Xfinity teams will be allowed eight sets for the entire weekend.
Here is the tire info:
Tire Codes: Left-side — D-4650; Right-side — D-4658
Tire Circumference: Left-side – 87.56 in. (2,224 mm); Right-side – 88.39 in. (2,245 mm)
Minimum Recommended Inflation (Cup): Left Front – 19 psi; Left Rear – 19 psi; Right Front – 45 psi; Right Rear – 42 psi
Minimum Recommended Inflation (Xfinity): Left Front – 21 psi; Left Rear – 19 psi;Right Front – 45 psi; Right Rear – 42 psi
This is the same combination of left and right-side tires Cup teams ran in this race last year. Xfinity teams ran this left-side tire at Auto Club in 2016, but this is their first time running this multi-zone tread right-side tire. Cup teams also ran this left-side tire at Indianapolis and Darlington last season, while Xfinity teams ran it at Pocono and Indianapolis.
This right-side code, being a multi-zone tread tire, features two distinct tread compounds on the same tire — one for endurance and heat resistance on the inboard two inches of the tread and one for traction on the outboard 10 inches. Like with all NASCAR ovals greater than 1 mile in length, teams are required to run liners in all four tire positions at Auto Club. Air pressure in those inner liners should be 12-25 psi greater than that of the outer tire.