When backing a truck, you should: Question When backing a truck, you should: Answers Only use the side mirrors on the driver’s side. Use both side mirrors. Only use the side mirrors on the passenger's side. Explanation Backing a commercial motor vehicle is always dangerous because you cannot see everything behind you. When backing, make frequent checks of the mirrors on both sides of the vehicle. This questions appears in the following tests: Alaska Double Arizona Passenger Idaho Passenger Louisiana Class A Knowledge Test South Dakota Passenger