Off-Tracking and Turns
Why the trailer wheels do not follow the tractor wheels, and how to use that to make safe turns.
Endorsement: Combination Vehicles · Source: FMCSA CDL Manual (public domain)
Off-tracking is the geometric reality that the rear axles of a trailer do not follow the same path as the tractor\'s steering axle through a turn. The longer the wheelbase between steering axle and trailer rear axle, the more the trailer cuts inside the tractor\'s path. On a 53-foot trailer, the difference can be more than 12 feet at a tight intersection. The CDL exam treats this as fundamental physics that every Class A driver must internalize.
To turn right at a typical intersection without curbing the trailer wheels, the FMCSA-recommended technique is to swing slightly to the left of your normal lane position, then turn right wide enough that the trailer\'s rear wheels clear the curb on the inside of the turn. The challenge is to swing only as much as needed; swinging too far left invites another driver to squeeze up your right side, where they will be in your blind spot when you complete the turn. Watch your right mirror constantly during the turn to ensure the trailer is tracking where you intend.
Left turns require entering the intersection in the leftmost lane that is legal for your direction of travel and exiting into the leftmost lane on the receiving street. If you start the turn from the second lane, the trailer will track into the curb on the inside of the turn. The exam also tests turning at very tight intersections and on narrow streets; the correct technique is sometimes to make a button-hook turn (initially turning the wrong way to get the angle, then completing the turn) or to refuse the route and find an alternate. Off-tracking applies in reverse during backing: the trailer will track in the opposite direction of the tractor\'s steering input, and small steering corrections create large trailer movements at low speed.
Key terms to memorize
- fifth wheel
- kingpin
- glad hands
- tractor protection valve
- off-tracking
- jackknife
- trailer hand valve
Other Combination Vehicles topics
- Coupling and Uncoupling — The full step-by-step procedure for safely connecting and disconnecting a tractor and semitrailer.
- Trailer Brake Systems — How trailer brakes connect to the tractor, what the hand valve does, and why you almost never use it.
- Rollover Prevention — Why combination vehicles roll over so easily and how to keep yours upright.
- Antilock Brake Systems (ABS) — What ABS does, what it does not do, and how to drive a combination with mixed ABS coverage.
Test what you learned
Now that you have the Off-Tracking and Turns material in your head, drill the Combination Vehicles practice test. The questions are drawn from the same FMCSA source material this article paraphrases. For state-specific framing, jump to your state page and pick the Combination Vehicles test for your jurisdiction.