California law requires the combined vehicle and trailer length not be longer than 40 feet except for a semitrailer towed by a tractor truck and a vehicle weighing less than 4,000 pounds may not tow a vehicle weighing more than 6,000 pounds, according to the California Department of Transportation. California law also gives cities and counties the right to ban vehicle and trailer combinations longer than 60 feet on highways within their jurisdictions.
California law requires drivers towing a double trailer obtain the double trailer endorsement on their Class A commercial driver's license, describes the California Department of Transportation. Drivers must have a Class A license if they tow any vehicles with a gross vehicle rating over 10,000 pounds. They must also be over age 18 and have a current medical certificate.
The state also defines maximum lengths for tractor truck and semitrailer combinations. A tractor truck towing a double semitrailer cannot exceed 75 feet of total length, with each trailer no longer than 28.5 feet. This length excludes dock bumpers, nose standown brackets and fifth wheel side ramps. A motor truck and semitrailer combination may not exceed 65 feet of total length, with the semitrailer no longer than 34 feet, according to the California Department of Transportation.