Turns, Lane Changes, and Offtracking
Combination vehicles turn differently from cars, and this domain tests spatial reasoning. Offtracking is the difference between the path of the front wheels and the rear wheels; the rear of a long trailer cuts inside the turn, so you must swing wide and check mirrors throughout. Know that right turns are the dangerous ones: the trailer's rear wheels can climb a curb or strike a pedestrian or sign, so approach from the proper lane, turn slowly, and watch the right mirror. Left turns require you to move into the correct lane and avoid cutting the corner.
Lane changes demand more than a mirror check: use the mirrors, signal early, check blind spots on both sides, and remember that the trailer tracks behind and can be hidden. Rearward amplification means a quick lane change whips the trailer; make smooth, gradual moves. Traps: questions implying a car will see your turn signals (they may not - signal early and check), questions about tail swing when the tractor turns (the rear of the tractor can swing out), and questions about which mirror shows the trailer's rear wheels (the flat mirrors, adjusted to see the trailer).
Rule of thumb: for a right turn, swing wide enough that the trailer's rear wheels clear the curb, but not so wide that you enter another lane. Turn from the lane you are in, go slow, and watch the right mirror until the trailer clears.
Also know that offtracking increases with wheelbase and with the number of trailers, so a double trailer cuts in more than a single.