Vehicle Code section 5155
(a)
Except as provided in Section 5161, the license plate for a passenger vehicle, commercial vehicle, or trailer shall provide a space not larger than two inches by three inches to the left of the numerical series and a space not larger than five-eighths of an inch in height below the numerical series for a distinctive design, decal, or descriptive message as authorized by this article. The license plates shall be issued in sequential numerical order or, pursuant to Section 5103, in a combination of numbers or letters.(b)
Specialized license plates authorized under this article may be issued for use on a motorcycle. That license plate shall contain a five-digit configuration issued in sequential numerical order or, pursuant to Section 5103, in a combination of numbers or letters. There shall be a space to the left of the numerical series for a distinctive design or decal and the characters shall contrast sharply with the uniform background color. A motorcycle plate containing a full plate graphic design is not authorized.(c)
Specialized license plates may be issued as environmental license plates, as defined in Section 5103.
Source:
Section 5155, https://leginfo.legislature.ca.gov/faces/codes_displaySection.xhtml?lawCode=VEH§ionNum=5155. (accessed Apr. 24, 2025).