Tennessee Code Title 55. Motor and Other Vehicles § 55-4-124

(a) Any vehicle, freight motor vehicle, truck-tractor, trailer or semitrailer or combinations of these vehicles that transports crushed stone, fill dirt and rock, soil, bulk sand, coal, clay, shale, phosphate muck, asphalt, concrete, other building materials, forest products, unfinished lumber, ferrous and nonferrous scrap metal, agricultural lime, liquid fertilizer, solid waste, coal ash and agricultural products shall be permitted to register as follows:

(b) If the commissioner of transportation is formally notified by an appropriate federal official that, as a result of any provision of this section, the state will lose federal funds, then the provision shall be void and inoperative.

(c) Nothing contained in this section shall be construed as authorizing these vehicles to use that portion of the state highway system designated as the interstate system.