Pinewood Derby is a Cub Scout racing event. Cub scouts create small cars, usually from kits that contain a piece of pine (hence the name, pinewood), 4 plastic tires, and 4 nails to use as the axles. The size of the wood is regulated to be no larger than 7 inches long and 2 3/4 inches wide. The finished car can weigh no more than 5 ounces. Local troops may have variations on these specifications.