(a) The commissioner shall determine the gross weight of each motor vehicle which is eligible for commercial registration, including each tractor equipped with rubber tires and, for the purpose of computing fees, gross weight shall be the weight of the vehicle in pounds plus the rated load capacity in pounds as determined by the commissioner, provided, in the case of a tractor restricted for use with a trailer, registered as a heavy duty trailer, the fee shall be based on the gross weight of the tractor which shall be the light weight of such tractor; and said commissioner shall collect fees for registration based on such gross weight, as follows: When all surfaces in contact with the ground are equipped with pneumatic tires, the fee for such motor vehicle or tractor of gross weight not exceeding twenty thousand pounds shall be one dollar and sixteen cents, for each one hundred pounds or fraction thereof; from twenty thousand and one pounds up to and including thirty thousand pounds, one dollar and forty-two cents, for each one hundred pounds or fraction thereof; from thirty thousand and one pounds up to and including seventy-three thousand pounds, one dollar and seventy-seven cents, for each one hundred pounds or fraction thereof; from seventy-three thousand and one pounds and over, one dollar and ninety-two cents, for each one hundred pounds or fraction thereof. In addition to any other fee required under this subsection, a fee of ten dollars shall be collected for the registration of each motor vehicle subject to this subsection.

      (b) The minimum fee for any commercial registration or registration of a tractor equipped with pneumatic tires shall be forty-four dollars.

      (c) For the registration of each motor vehicle classed as an artesian well driller or well drilling equipment, however mounted, when equipped with rubber tires, the fee shall be forty dollars per annum whether the license is issued for the license year or only a portion thereof. On and after July 1, 1992, the fee shall be forty-six dollars.

      (d) For the registration of a motor vehicle equipped with a wood saw rig, if it is used for that purpose only, or a motor vehicle equipped with a spray rig used exclusively for spraying fruit trees or shrubs, when equipped with rubber tires, the fee shall be twenty-two dollars per annum whether the license is issued for the license year or only a portion thereof. On and after July 1, 1992, the fee shall be twenty-five dollars.

      (e) For all other motor vehicles which are eligible for commercial registration, including tractors equipped with rubber tires other than pneumatic tires, the fee shall be, for each such vehicle or tractor of gross weight (1) not exceeding twenty thousand pounds, one dollar and fifty cents, and on and after July 1, 1992, one dollar and seventy-five cents, for each one hundred pounds or fraction thereof, and (2) from twenty thousand and one pounds up to and including twenty-six thousand pounds, two dollars, and on and after July 1, 1992, two dollars and twenty-five cents, for each one hundred pounds or fraction thereof. The minimum fee for any such motor vehicle or tractor shall be fifty dollars. On and after July 1, 1992, the minimum fee shall be fifty-six dollars.