When changing lanes in a doubles combination, you should:

Lane changes in doubles and triples require special care because of rearward amplification. Signal well in advance (at least 5-6 seconds at highway speed), check all mirrors carefully (the rear trailer has the largest blind spots in the combination), and steer smoothly and gradually rather than crisply. A lane change that takes 4-5 seconds is appropriate; a 2-second lane change is dangerous. Avoid double lane changes (moving across two lanes in one maneuver) because the steering inputs are amplified by both trailers in sequence. Avoid lane changes in turbulent crosswind conditions, on icy roads, and when speed differential to other traffic is high.