CHARLOTTE, N.C. (AP) — NASCAR has changed the rules on its aerodynamic package for short tracks and road courses because the racing didn’t improve at those venues under rules introduced last season.

NASCAR had been fairly adamant the rules package would remain unchanged but reversed course late last season when it was evident the racing clearly had suffered at smaller tracks.

Teams will now use a separate rules package at Bristol, Dover, Martinsville, New Hampshire, Phoenix, Richmond, the Charlotte Roval, Sonoma and Watkins Glen. The changes include a significantly smaller rear spoiler, which shrinks from an 8-inch height to 2.75 inches. The front splitter’s overhang will now measure a quarter-inch (down from 2 inches), with approximately 2-inch wings (reduced from 10.5 inches).

There will be alterations to the radiator pan by removing its vertical fencing in an effort to reduce front-end downforce. The dimensions of the pan remain the same.