Section 22406. Maximum Speed for Designated Vehicles

(a) No person may drive any of the following vehicles on a highway at a speed in excess of 55 miles per hour:

(1) A motortruck or truck tractor having three or more axles or any motortruck or truck tractor drawing any other vehicle.

(2) A passenger vehicle or bus drawing any other vehicle.

(3) A schoolbus transporting any school pupil.

(4) A farm labor vehicle when transporting passengers.

(5) A vehicle transporting explosives.

(6) A trailer bus, as defined in Section 636.

(b) Any person who operates a commercial motor vehicle, as defined in Section 15210, upon a highway at a speed exceeding a maximum speed limit established under this code by 15 miles per hour or more, is guilty of a misdemeanor. A violation of this subdivision shall be considered a "serious traffic violation," as defined in subdivision (i) of Section 15210, and shall be subject to the sanctions provided under Section 15306 or 15308, in addition to any other penalty provided by law.