California Code, Vehicle Code - VEH § 26307

No forklift truck manufactured after January 1, 1970, shall be towed behind another vehicle unless it is equipped with brakes on the wheels of the rearmost axle when the forklift truck is in the towing position, which brakes shall be adequate, supplemental to the brakes on the towing vehicle, to enable the combination of vehicles to comply with the stopping distance requirements of Section 26454.