Section 22406 Of Article 2. Other Speed Laws From California Vehicle Code >> Division 11. >> Chapter 7. >> Article 2.

. No person may drive any of the following vehicles on a highway at a speed in excess of 55 miles per hour:
  (a) A motortruck or truck tractor having three or more axles or any motortruck or truck tractor drawing any other vehicle.
  (b) A passenger vehicle or bus drawing any other vehicle.
  (c) A schoolbus transporting any school pupil.
  (d) A farm labor vehicle when transporting passengers.
  (e) A vehicle transporting explosives.
  (f) A trailer bus, as defined in Section 636.