Drive Wheel Fairings
The aerodynamics associated with rotating tires and wheels are complicated by many factors. Drive wheel fairings mounted between and behind the drive wheels of the tractor streamline the airflow around the rotating tires and direct airflow as it leaves the tractor. They provide a net benefit to the fuel economy of the vehicle, and are often used in combination with wheel covers on the tractor for a higher net benefit. Fuel savings for these devices are estimated to be about 2%.
It is also believed that these devices improve appearance and help reduce water spray.
Fuel Savings (If Coupled with Higher Capacity and Higher Voltage Electrical System)
Not Available for Most Vehicles as of March 2017
Increased Complexity of Electrical System
Higher Electrical System Voltage and Power Output Required
Increased Maintenance Costs