1. (a) Under the unloaded weight method the tax on a truck or tractor is computed by determining the rate of tax from the table set forth in section 481.10, infra, based on the unloaded weight of the truck or tractor and by multiplying the total mileage operated within the State by such rate.

2. (b) The applicable rate of tax for a truck is determined by the unloaded weight as set forth in the permit. The same rate is applicable whether the truck is operated with or without a load.

   Example:

   If the unloaded weight of a truck if 8,500 pounds, the applicable tax rate if $.004, whether it carries a load of 5,000 or 10,000 pounds. If it travels 100 miles the tax is computed as follows:

   100 × $.004 = $.40

3. (c) The applicable rate of tax for a tractor is determined by its unloaded weight as set forth in its permit, whether it is operated alone or in combination with another motor vehicle.

   Example:

   A tractor with an unloaded weight of 6,000 pounds travels 50 miles, a trailer with a maximum gross weight of 25,000 pounds is then attached and the tractor-trailer combination travels 50 miles. The applicable tax rate for the entire trip is $.010. The tax is computed as follows:

   100 × $.010 = $1.00

4. (d) Although the tax is based on unloaded weight as set forth in the permit, nevertheless if the actual unloaded weight is in excess of that set forth in the permit, the tax must be computed at the rate applicable to the actual weight. In such case, an amended permit must be obtained. (See § 473.6, supra.)
5. (e) Where an amended permit is issued on the basis of a decrease in unloaded weight, the unloaded weight set forth in the amended permit is not effective for tax purposes until the superseded permit is surrendered to the State Tax Commission. (See § 473.5, supra.)

Tax Law, § 503(3)