Vehicle Code § 27904

There shall be displayed in a conspicuous place on both the right and left sides of a pilot car a sign showing the name of the company which owns or operates the pilot car. The name shall contrast with the background and shall be of a size, shape, and color as to be readily legible during daylight hours from a distance of 50 feet. Additional markings which do not interfere with the legibility of the name may also be displayed.