No vehicle operating either on the public right of way or on private property shall exceed the maximum sound pressure level of eighty decibels dB(A), except that for vehicles over a gross volume weight of 8,000 pounds on a state highway or a prescribed truck route, or in commercial or industrial zones that are not adjacent to a residential zone, the maximum sound pressure level shall not exceed eighty-eight decibels dB(A).
(1964 Code Sec. 99.11)