(a) The load upon any vehicle operated alone, or the load upon the front vehicle of a combination of vehicles, shall not extend more than three feet beyond the front wheels of such vehicle or the front bumper of such vehicle if it is equipped with a bumper.
(b) Any vehicle or combination of vehicles transporting passenger vehicles or other motor vehicles may carry a load which extends no more than four feet beyond the front and six feet beyond the rear of the transporting vehicle or combination of vehicles.