Question Items on a flatbed: Answers Are usually heavy enough to not need to be strapped down. Should not be strapped down if you are driving more slowly than 35 mph. Must always be secured. Explanation On flatbed trailers and trailers without sides, cargo must be tied down to prevent it from shifting or falling off in transit. Take a FREE Practice Test Now This questions appears in the following tests: Alaska Knowledge Test Class A , Oklahoma Knowledge Test Class A , Alabama Knowledge Test Class B , Vermont Knowledge Test Class B ,