For the purposes of the rules in Part 5—Equipment and Drivers, "commercial motor vehicle" means any self-propelled or towed motor vehicle used on a highway when the vehicle:

(1) Has a gross vehicle weight rating or gross combination weight rating, or gross vehicle weight or gross combination weight, of ten thousand and one pounds or more, whichever is greater; or

(2) Is used in transporting material found by the Secretary of Transportation to be hazardous under 49 U.S.C. 5103 and transported in a quantity requiring placarding under regulations prescribed by the Secretary under 49 C.F.R., subtitle B, chapter I, subchapter C.