CA SB12

Amends Vehicle Code Section 35110 to allow aerodynamic devices to extend 3 inches on each side of tractor-trailer vehicles, in addition to existing allowances for door handles, hinges, cable cinchers, chain binders, and hazardous materials placards.

Defines "aerodynamic devices" as technologies that minimize drag and improve airflow, including gap fairings between tractor and trailer, side skirts under the trailer, and rear fairings that reduce turbulence at the trailer's rear.

Requires aerodynamic devices to not adversely impact vehicle swept width and turning characteristics and prohibits devices whose primary purpose is advertising.