>5. No motor vehicle or trailer shall be operated on any highway of this state unless it shall have displayed thereon the license plate or set of license plates issued by the director of revenue or the state highways and transportation commission and authorized by section 301.140. Each such plate shall be securely fastened to the motor vehicle or trailer in a manner so that all parts thereof shall be plainly visible and reasonably clean so that the reflective qualities thereof are not impaired. Each such plate may be encased in a transparent cover so long as the plate is plainly visible and its reflective qualities are not impaired. License plates shall be fastened to all motor vehicles except trucks, tractors, truck tractors or truck-tractors licensed in excess of twelve thousand pounds on the front and rear of such vehicles not less than eight nor more than forty-eight inches above the ground, with the letters and numbers thereon right side up. The license plates on trailers, motorcycles, motortricycles, autocycles, and motorscooters shall be displayed on the rear of such vehicles either horizontally or vertically, with the letters and numbers plainly visible. The license plate on buses, other than school buses, and on trucks, tractors, truck tractors or truck-tractors licensed in excess of twelve thousand pounds shall be displayed on the front of such vehicles not less than eight nor more than forty-eight inches above the ground, with the letters and numbers thereon right side up or if two plates are issued for the vehicle pursuant to subsection 3 of this section, displayed in the same manner on the front and rear of such vehicles. The license plate or plates authorized by section 301.140, when properly attached, shall be prima facie evidence that the required fees have been paid. So, have a >=6 Ton towing capacity, you only get a front plate. This can be done with a F250, for example. Good ole boy loophole.