28-709. Maximum speed limit for large vehicles and vehicles with trailers A. Unless a lower maximum speed limit is posted or the department designates a greater maximum speed limit pursuant to subsection B of this section, a person shall not drive either of the following on a highway in this state at a speed that is greater than sixty-five miles per hour: 1. A motor vehicle or vehicle combination with a declared gross weight of more than twenty-six thousand pounds, excluding a motor vehicle designed for carrying sixteen or more passengers, including the driver. For the purposes of this paragraph, ' declared gross weight' and ' vehicle combination' have the same meaning prescribed in section 28-5431. 2. A vehicle that is drawing a pole trailer that weighs six thousand or more pounds. B. If the department determines on the basis of an engineering and traffic investigation of a highway under its jurisdiction that the designation of a maximum speed limit for vehicles prescribed in subsection A of this section that is greater than sixty-five miles per hour would facilitate the safe and orderly movement of traffic, the department may designate such a maximum speed for travel of those ction A of this section that is greater than sixty-five miles per hour would facilitate the safe and orderly movement of traffic, the department may designate such a maximum speed for travel of those vehicles and shall erect signs at reasonable intervals giving notice of the speed limitation.
Arizona Legal Code