Here's how your Tennesee laws are written.
http://www.tn.gov/sos/rules/1340/1340-01/1340-01-13.pdf
2. Commercial driver licenses are not required for drivers who operate the vehicles described below, under the conditions specified for each:
(a) Vehicles which are controlled and operated by a farmer or nurseryman that are used to transport either agricultural products, farm machinery, or farm supplies to or from a farm or nursery, and are not used in the operations of a common or contract motor carrier and are used within one hundred fifty (150) miles of the person’s farm or nursery;
(b) Vehicles designed and used solely as emergency vehicles which are necessary for the preservation of life or property, or the execution of emergency governmental functions performed under emergency conditions and not subject to normal traffic regulation. This exemption shall apply to vehicles operated by paid or non-paid personnel;
(c) Vehicles of the United States Department of Defense when operated by military personnel on active duty, members of the Reserves and National Guard on active duty including personnel on full-time National Guard duty, personnel on part-time training and National Guard military technicians or civilians who are required to wear military uniforms and are subject to the code of military justice;
(d) Vehicles designed and used primarily as recreational vehicles as defined in 1340-1-13- .02; or (see reference below)
(e) Vehicles leased strictly and exclusively to transport personal possessions or family members for non-business purposes. (U'haul exemption)
(3) Drivers who operate the vehicles described in subpart (2) above must comply with all requirements specified elsewhere in 1340-1-13-.03 and 1340-1-13-.04 for a Class D license with the proper endorsement. (see reference below)
(4) For up to six (6) months, non U.S. citizens who are employed in managerial or technical positions in this State may operate under a valid driver’s license issued by another state, country, or international body.
(9) Commercial Motor Vehicle means a motor vehicle or combination of motor vehicles used in commerce to transport passengers or property if the motor vehicle:
(a) has a gross vehicle weight rating (G.V.W.R.) or gross combination weight rating (G.C.W.R.) in excess of twenty-six thousand (26,000) pounds;
(b) is designed to transport more than fifteen (15) passengers, including the driver;
(c) is of any size and used in the transportation of materials found to be hazardous for the purposes of the Hazardous Materials Transportation Act, 49 U.S.C. App. 1801 et seq., and which must be placarded, under the Hazardous Materials Regulations 49 C.F.R. § 172.500 et seq. (1993); or
(d) is used as a school bus.
Recreational Vehicle means every motor vehicle primarily designed as temporary living
quarters for recreational camping or travel, as defined in American National Standards Institute (ANSI) Standards A 119.2 and A 119.5. The basic entities are: travel trailer, camping trailer, truck camper, motor home, and park trailer.
(d) Class D. The license which must be issued and valid for the operation of any single vehicle with a G.V.W.R. of twenty-six thousand (26,000) pounds or less, or any combination of vehicles with a G.C.W.R. of twenty six thousand (26,000) pounds or less, and are not included in the definitions of Class A, B, C or M.
Authority: T.C.A. §§55-50-102, 55-50-304, 49 C.F.R. §383 (1992), and Title XII, Public Law 99-570, §12013. Administrative History: Original rule filed April 8, 1996; effective August 28, 1996.
