NASCAR will use a reduced-downforce package that could cut downforce by 25 percent at a July 11 race at Kentucky Speedway as it seeks to produce more passing for the lead and more off-throttle time in the corners.
Whether NASCAR will implement the new rules for future races at 1.5-mile tracks such as Kentucky or other similar circuits where downforce plays a critical role is still to be determined, NASCAR executive vice president Steve O'Donnell said Tuesday.
"We've been very, very vigilant in talking about tighter racing," O'Donnell said Tuesday. "I think we've achieved that in terms of first to 43rd. You see that those teams are closer than ever, but we certainly want to see more lead changes on the racetrack.
"We'll evaluate not only that but a number of different factors coming out of Kentucky and see what we can learn and potentially what we can implement down the road."
The new rules reduce the spoiler height from 6 inches to 3.5 inches, the radiator pan width from 38 inches to 25 inches and the front splitter overhang by 1.75 inches.
Teams will have four hours of test time July 8 at Kentucky, two days before the official race weekend begins, to work with the changes that some drivers have lobbied for all year after being frustrated with what seems to be less ability to pass this season than in 2014.
After reducing horsepower from 850-900 to 725 and downforce from about 3,500 pounds to approximately 3,200 pounds for 2015, NASCAR had said at the beginning of the season that it hoped to lower downforce by another 20-25 percent (700 pounds or more) for 2016. It hoped to have those 2016 rules set possibly by no later than this August.
The aerodynamic rules for Kentucky could reach that reduced downforce goal, although teams will start working immediately to find ways to increase downforce.
The problem with announcing the changes so close to the Kentucky race is whether Goodyear, which pays NASCAR to be its sole tire provider, can make a quality educated guess of the best-manufactured tire to deal with the reduced downforce.
O'Donnell said it will be a softer tire than the teams had a year ago, but not one made for the specific package announced Wednesday.
It is too late for Goodyear to do a test and manufacture the approximately 2,500 tires it would need for the race weekend. For Kentucky, Goodyear will bring the same left-side tire it had at Texas and Dover this year and a new right-side tire that hasn't been used.
O'Donnell said one benefit from the limited time between the announcement of the rules and the implementation of them on the race track is it would keep teams from extensive wind-tunnel testing, which he said could be an "equalizer" on the racetrack.