(2) The tax rate which shall apply to each motor vehicle shall be based upon the declared combined weight of the motor vehicle and in accordance with the weight group tax rates as shown in the tables set forth in ORS 825.476.
(3) For the purpose of computing the tax due:
(a) Table "A" applies to motor vehicles subject to the tax imposed by this section that are not issued an annual variance permit under ORS 818.200 (1)(a) to (c) to operate with a combined weight of more than 80,000 pounds.
(b) Table "B" applies to motor vehicles subject to the tax imposed by this section that are issued or required to obtain an annual variance permit under ORS 818.200 (1)(a) to (c) to operate with a combined weight of more than 80,000 pounds.
(c) The declared combined weight shall be the combined weight, as defined in ORS 825.005, declared in the application for authority under ORS 825.100, subject to audit and approval by the Department of Transportation.
(d) In addition to any tax due under this chapter, motor vehicles that exceed the maximum vehicle weight limits for annual variance permits under ORS 818.200 (1)(a) to (c) are subject to the road use assessment fee imposed under ORS 818.225 for the entire motor vehicle weight, minus the road use assessment fee for the maximum vehicle weight allowed under the annual variance permit.
(4) The tax for each motor vehicle when table "A" or "B" is used shall be computed by multiplying the extreme mileage of travel in Oregon by the appropriate weight group tax rate as it appears in the table. [Formerly 767.815]