Texas Transportation Code - TRANSP § 545.106. Signals by Hand and Arm or by Signal Lamp

(1) using the hand and arm; or

(2) lighting signal lamps approved by the department.

(1) the distance from the center of the top of the steering post to the left outside limit of the body, cab, or load of the motor vehicle is more than two feet; or

(2) the distance from the center of the top of the steering post to the rear limit of the body or load, including the body or load of a combination of vehicles, is more than 14 feet.