Set limits: Cup: 3 sets for practice, 1 set for qualifying and 9 sets for the race (8 race sets plus 1 set transferred from qualifying or practice); Xfinity: 6 sets for the event; Truck: 5 sets for the event
Tire Codes: Left-side — D-4860; Right-side — D-4862
Tire Circumference: Left-side — 2,223 mm (87.52 in.); Right-side — 2,251 mm (88.62 in.)
Minimum Recommended Inflation: Left Front — 20 psi; Left Rear — 18 psi; Right Front — 43 psi; Right Rear — 40 psi
Storyline — PJ1 in the middle of it all at Bristol: The traction compound PJ1 has become a hot topic in NASCAR since more tracks have begun applying it to their racing surfaces. While there are misconceptions about “the sticky stuff,” the basic truth is that PJ1 is applied to a particular lane of a racetrack to give drivers an additional racing groove that is, in theory, equal to the “preferred” groove(s). At Bristol Motor Speedway this week — where the bottom lane is preferred early and the top lane comes in later as more cars run up there — PJ1 will be applied to the bottom lane to give drivers an “equal” opportunity to move up or down to pass their competitors. Once the substance is applied at the beginning of the tripleheader event, Goodyear, NASCAR and track officials will monitor and measure the level of grip in all three lanes on the track and determine when, how and where the PJ1 will be re-applied throughout the weekend.
“We have been working very closely with NASCAR and the tracks as the use of PJ1 has become more common on the circuit,” said Greg Stucker, Goodyear‘s director of racing. “We generally all come up with a plan, and then watch how things unfold over the weekend, also considering feedback from the drivers. After each day of the event, we run a friction trailer on all the lanes of the track to measure the traction level and how that changed since the beginning of that day. Then we determine if the PJ1 needs to be re-applied, whether the application patch should change at all and what the concentration level should be. The goal in all of this is to keep the grip level consistent throughout the weekend so teams know what racing conditions to expect. We, as an industry, are putting a lot of science behind this effort, with an end goal of improving the quality of racing for our fans.”
Notes — Cup, Xfinity return to Bristol on same tire set-up: Teams in all three NASCAR national series in action at Bristol this week will run the same Goodyear tire set-up . . . Monster Energy NASCAR Cup and Xfinity Series teams ran this same combination of left- and right-side tires at Bristol in April . . . this is the first time NASCAR Gander Outdoors Truck Series teams have run either of these two tire codes . . . compared to what the Trucks ran at Bristol last August, this tire set-up features construction updates on both sides of the car and a compound change on the left-side . . . this is the only track at which NASCAR teams will run either of these two tire codes in 2019 . . . unlike on most NASCAR ovals one mile or less in length, on which teams generally do not run inner liners in their tires, teams are required to run liners in their right-side tires only at Bristol . . . air pressure in those inner liners should be 12-25 psi greater than that of the outer tire.