Veh. Code, § 35401

(a) Except as provided in subdivisions (b), (c), and (d), a combination of vehicles coupled together, including attachments, may not exceed a total length of 65 feet.

(b) (1) A combination of vehicles coupled together, including attachments, that consists of a truck tractor, a semitrailer, and a semitrailer or trailer, may not exceed a total length of 75 feet, if the length of neither the semitrailers nor the trailer in the combination of vehicles exceeds 28 feet 6 inches.

(2) A B-train assembly is excluded from the measurement of semitrailer length when used between the first and second semitrailers of a truck tractor-semitrailer-semitrailer combination of vehicles. However, if there is no second semitrailer mounted to the B-train assembly, it shall be included in the length measurement of the semitrailer to which it is attached.

(c) (1) A tow truck in combination with a single disabled vehicle or a single abandoned vehicle that is authorized to travel on the highways by this chapter is exempt from subdivision (a) when operating under a valid annual transportation permit.

(2) A tow truck, in combination with a disabled or abandoned combination of vehicles that are authorized to travel on the highways by this chapter, is exempt from subdivision (a) when operating under a valid annual transportation permit and within a 100-mile radius of the location specified in the permit.

(3) A tow truck may exceed the 100-mile radius restriction imposed under paragraph (2) if a single trip permit is obtained from the Department of Transportation.

(d) A city or county may, by ordinance, prohibit a combination of vehicles of a total length in excess of 60 feet upon highways under its respective jurisdiction. The ordinance may not be effective until appropriate signs are erected indicating either the streets affected by the ordinance or the streets not affected, as the local authority determines will best serve to give notice of the ordinance.

(e) A city or county, upon a determination that a highway or portion of highway under its jurisdiction cannot, in consideration of public safety, sustain the operation of trailers or semitrailers of the maximum kingpin to rearmost axle distances permitted under Section 35400, may, by ordinance, establish lesser distances consistent with the maximum distances that the highway or highway portion can sustain, except that a city or county may not restrict the kingpin to rearmost axle measurement to less than 38 feet on those highways or highway portions. A city or county considering the adoption of an ordinance shall consider, but not be limited to, consideration of, all of the following:

(1) A comparison of the operating characteristics of the vehicles to be limited as compared to operating characteristics of other vehicles regulated by this code.

(2) Actual traffic volume.

(3) Frequency of accidents.

(4) Any other relevant data.

In addition, the city or county may appoint an advisory committee consisting of local representatives of those interests that are likely to be affected and shall consider the recommendations of the advisory committee in adopting the ordinance. The ordinance may not be effective until appropriate signs are erected indicating the highways or highway portions affected by the ordinance.

This subdivision shall only become operative upon the adoption of an enabling ordinance by a city or county.

(f) Whenever, in the judgment of the Department of Transportation, a state highway cannot, in consideration of public safety, sustain the operation of trailers or semitrailers of the maximum kingpin to rearmost axle distances permitted under Section 35400, the director, in consultation with the Department of the California Highway Patrol, shall compile data on total traffic volume, frequency of use by vehicles covered by this subdivision, accidents involving these vehicles, and other relevant data to assess whether these vehicles are a threat to public safety and should be excluded from the highway or highway segment. The study, containing the conclusions and recommendations of the director, shall be submitted to the Secretary of the Business, Transportation and Housing Agency. Unless otherwise notified by the secretary, the director shall hold public hearings in accordance with the procedures set forth in Article 3 (commencing with Section 35650) of Chapter 5 for the purpose of determining the maximum kingpin to rear axle length, which shall be not less than 38 feet, that the highway or highway segment can sustain without unreasonable threat to the safety of the public. Upon the basis of the findings, the Director of Transportation shall declare in writing the maximum kingpin to rear axle lengths which can be maintained with safety upon the highway. Following the declaration of maximum lengths as provided by this subdivision, the Department of Transportation shall erect suitable signs at each end of the affected portion of the highway and at any other points that the Department of Transportation determines to be necessary to give adequate notice of the length limits.

The Department of Transportation, in consultation with the Department of the California Highway Patrol, shall compile traffic volume, geometric, and other relevant data, to assess the maximum kingpin to rearmost axle distance of vehicle combinations appropriate for those state highways or portion of highways, affected by this section, that cannot safely accommodate trailers or semitrailers of the maximum kingpin to rearmost axle distances permitted under Section 35400. The department shall erect suitable signs appropriately restricting truck travel on those highways, or portions of highways.

(g) This section shall become operative on January 1, 2010.