Every new motor vehicle sold after September 6, 1941, and operated on a street, other than vehicles of the type mentioned in Section 337.06 or a commercial tractor to which a trailer or semitrailer is attached, shall carry at the rear, either as a part of the tail lights or separately, two red reflectors of such size and characteristics and so maintained as to be visible at night from all distances within 300 feet to fifty feet from such vehicle.