Tennessee Code Title 67. Taxes and Licenses § 67-6-331

(a) There shall be exempt from the tax imposed by this chapter, the transfer, by any dealer in personal property, of motor vehicles with a gross vehicle weight rating (GVWR) of a Class three (3) or above as defined in § 55-4-113 and trailers, semi-trailers and pole-trailers as defined in §§ 55-1-105 and 55-4-113 that shall be used to transport passengers or cargo principally in interstate or foreign commerce by a carrier holding common or contract carrier operating authority granted by the federal government or other state regulatory agency.

(b) “Principally,” as used in subsection (a), means more than fifty percent (50%) of the use of the vehicle.

(c) A motor vehicle is used to transport passengers or cargo in interstate or foreign commerce if it transports passengers or cargo moving from a point of origin in another state or foreign country to a point of destination within this state, or vice versa; or moving through this state from a point of origin in another state or foreign country to a point of destination in a different state or foreign country.