Yes, each motor carrier required to register must carry a copy of the current Certificate of Registration issued by PHMSA or another document bearing the registration number identified as the “U.S. DOT Hazmat Reg. No.” on board each truck and truck tractor (not including trailers and semi-trailers) used to transport hazardous materials subject to the requirements of this subpart. The Certificate of Registration or document bearing the registration number must be made available, upon request, to enforcement personnel [107.620(b)].