NASCAR announced late Friday night that it will add 18 inches of resin to the lower groove in each of the four corners to enhance Saturday night's Sprint Cup race at Bristol Motor Speedway. The substance is intended to give the lower line additional grip to make that groove as competitive as the top groove.
"It was a collaboration between the track, (NASCAR) and the industry," said NASCAR spokesman Kurt Culbert of the decision. "(The resin) seemed to work really well."
While the lower groove was used throughout Friday night's Xfinity race, the preferred groove was the high line. Still, drivers could run on the lower groove and not lose as much time as previously. The track's lower groove in the corners was treated before this week. Resin was added after Wednesday night's Camping World Truck Series race. NBC