For purposes of this Subchapter, the word tractor means a self-propelled vehicle used for drawing other vehicles and not primarily constructed to carry a load independently. For example, a vehicle which is principally used for drawing other vehicles is a tractor, even if it is equipped with a rack enabling it to independently carry a load.
N.Y. Comp. Codes R. & Regs. Tit. 20 § 470.3