Summarized here are the California Vehicle Code (CVC) sections related to vehicle width. Some of the CVC sections on this web page are paraphrased for brevity. For the full legal wording, please go to the on-line CVC Width Sections 35100-35111.
35100. (a) The total outside width of any vehicle or its load shall not exceed 102 inches.
35100.1. (a) The metric equivalent of 102 inches is 2.6 meters.
(b) The width measurement of any vehicle with side walls shall be made from the outside wall of the two opposite sides of the vehicle.
CITIES & COUNTIES
35100. (c) A city or county may prohibit a width in excess of 96 inches upon highways under its jurisdiction.
35105. Any city organized under a freeholders' charter may permit a width in excess of these limits when used within the city.
VEHICLE & LOAD EXEMPTIONS
35101. When any vehicle is equipped with pneumatic tires, the maximum width from the outside of one wheel and tire to the opposite shall not exceed 108 inches.
35100.5. The outside width of a cotton module mover and the load thereon shall not exceed 130 inches in width. For details, see the web page: Cotton Module Movers.
35102. When any vehicle carries a load of loosely piled agricultural products such as hay, straw, or leguminous plants in bulk but not crated, baled, boxed, or sacked, the load shall not exceed 120 inches in width.
35104. The following vehicles shall not exceed a width of 120 inches: (a) Special mobile equipment. (b) Special construction or highway maintenance equipment. (c) Motor vehicles for hauling feed for livestock that are exempted from registration, except when operated on a highway during darkness.
35111. No passenger vehicle shall be operated on any highway with any load extending beyond the line of the fenders on its left side or more than six inches beyond the line of the fenders on its right side.
35106. (a) Motor coaches or buses may have a maximum width of 102 inches.
(b) Motor coaches or buses operated under the jurisdiction of the Public Utilities Commission (PUC) in urban or suburban service may have a maximum outside width of 104 inches, when approved by the PUC. Motor coaches or buses operated by common carriers of passengers for hire in urban or suburban service and not under the jurisdiction of the Public Utilities Commission may have a maximum outside width not exceeding 104 inches.
(c) "Urban and suburban service" means in urban or suburban areas, or between municipalities if the one-way route mileage is no more than 50 miles.
(b) Motor coach routes over state highways outside limits of incorporated cities where the one-way route mileage is over 25 miles, but does not exceed 50 miles, shall be approved by the Department of Transportation.
35100. (b) Safety devices shall not be included in the calculation of width. (For more information on safety devices, see "SAFETY DEVICES" below.)
35103. (a) A recreational vehicle may exceed the maximum width if the excess width is from an appurtenance that does not exceed six inches beyond either sidewall. (b) An appurtenance is an integral part of a vehicle and includes awnings, grab handles, lighting equipment, cameras, and vents. An appurtenance may not be used as a load carrying device.
35109. Lights, mirrors, or devices which are required may extend beyond the permissible width no more than 10 inches on each side.
35110. Door handles, hinges, cable cinchers, chain binders, and holders for placards warning of hazardous materials may extend three inches on each side of the vehicle.
SAFETY DEVICES: According to The California Highway Patrol's Commercial Enforcement Manual "HPM" 82.6 Chapter 8, Revised March 2001, "Size and Weight, Section 1(b)(5):
(a) The maximum permitted width for the items listed in this section is 108 inches, however, they shall not exceed three inches beyond either side of the vehicle.
(b) Safety devices that are excluded from determination of vehicle width include the following: door handles, cable cinchers, chain binders, corner caps, rear and side door hinges and their protective hardware, rain gutters, side marker lamps, lift pads for 'piggyback' trailers, tarps and tarp hardware, tiedown assemblies on platform trailers, wall variations from true flat, weevil pins, and sockets on low bed trailers.
(c) The exemption granted in this section applies only to the listed items and does not include stake pockets, stakes, and other items of equipment.
The California Code of Regulations (CCR) allows fire trucks to have a maximum width of 120 inches. See "Fire Truck Exemptions" in CCR Section 1411.7 (g). The pertinent statement is copied below:
(g) Fire trucks may exceed width limitations provided in Division 15 of the California Vehicle Code but cannot exceed 120 inches.
IMPLEMENTS OF HUSBANDRY
Various types of farm equipment have exemptions for width, length, height, and weight. See California Vehicle Code Sections 36660 through 36627.