Abstract: An under trailer aerodynamic control system that increases air mass, organization and velocity with forward mounted airflow modifying directional panels and a rear airflow modifier mounted in a firm and movable manner for location near the underneath side of a truck trailer forward of the trailer tires and axles to better manage airflow around the trailer tire and axle assembly. In operation, the rear mounted airflow modifier collects the airflow from the forward mounted modifiers and routs impinging air to exit between the trailer tires and well past the end of the trailer for controlled road spray and splash while keeping tires and brakes running cooler and decreasing parasitic drag of the trailer as it moves along the highway while reducing driver fatigue due to improved handling characteristics.