Vehicles in all three of NASCAR’s national series will carry the same tire sizes and compounds for this week’s three races at Bristol Motor Speedway.
One of the key storylines is the use of PJ1 traction compound, which 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, the bottom lane is considered the preferred lane early in each race before the top lane becomes the preferred lane later on.
As a result, Bristol track officials will apply PJ1 to the bottom lane to give drivers an “equal” opportunity to move up or down to pass their competitors, according to this week’s Goodyear Racing media release.
“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.”
Here’s the tire info for all three races:
Tire: Goodyear Eagle Speedway Radials.
Set limits: Cup: Three sets for practice, one set for qualifying and nine sets for the race (eight race sets plus one set transferred from qualifying or practice); Xfinity: six sets for the event; Truck: five 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.
Notes: 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.