(1) The value specified by the manufacturer of the power unit of a vehicle, if:
(a) The value is displayed on the Federal Motor Vehicle Safety Standards certification label; and
(b) The vehicle is towing another unit; or
(2) The sum of the gross vehicle weight ratings or gross vehicle weights of the power unit and the towed unit, or any combination thereof, that produces the highest value. [1989 c.636 §4; 2017 c.190 §9]