Tax Law, § 501, subd. 2; § 503-a, subd. 1, 9
Example 1:
A snow plow, which is used for no other purpose, is not a motor vehicle regardless of its maximum gross weight or unloaded weight, and is therefore not required to have a permit.
Example 2:
A road building machine, with an unloaded weight of 25,000 pounds, is used for road building operations and is also used in transport materials to customers. It is excluded from the definition of motor vehicle only when used for road building operations. When it is used for any other purpose it is a motor vehicle. Therefore, a permit and plate should be obtained for such motor vehicle. The mileage of the vehicle when it is used as a road building machine is not subject to tax but its mileage when being used for any other purpose is taxable.
N.Y. Comp. Codes R. & Regs. Tit. 20 § 471.2