A special purpose commercial vehicle is a vehicle or combination of vehicles of unusual construction or design, self-propelled, primarily used off-highway or on road and bridge building and maintenance, which only travels on the public highways incidentally between off-highway or road building or maintenance jobs and which vehicle is primarily a machine, not a transporter of cargo, or is a truck used to transport and spread or spray agricultural chemicals.
N.Y. Comp. Codes R. & Regs. Tit. 15 § 105.2