R.I. Gen. Laws § 44-18-40: Exemption for buses, trucks and trailers in interstate commerce.

(a) Notwithstanding any provision of the general laws to the contrary, the purchase, rental or lease of a truck, or trailer by a trucking company is not subject to the provisions of the sales and use taxes imposed by this chapter on the condition that the truck and/or trailer is utilized exclusively in interstate commerce.

(b) Notwithstanding any provision of the law or regulation to the contrary, the operation of a bus by a bus company in interstate commerce shall not be subject to the provisions of the sales and use tax imposed by this chapter, on the condition that the bus is used eighty percent (80%) or more of the time in interstate commerce and provided that the bus company shall provide a properly executed affidavit attesting to the fact that the bus is used no less than eighty percent (80%) of the time in interstate commerce.