Tenn. Code Ann. § 67-6-343

There is exempt from the sales tax the retail sale of motor vehicles subject to registration and titling in this state pursuant to § 55-3-101 that are not registered and titled in this state, but are removed for use in another state within three (3) calendar days of purchase. Use of such motor vehicles within this state subsequent to purchase, but prior to removal from the state, does not constitute a use subject to tax. For the purposes of this section, vehicles subject to registration and titling in this state pursuant to § 55-3-101 are deemed to include all off-highway motor vehicles, as defined in § 55-3-101(c)(2).