247SimpleTests
CDL · Driving Combination Vehicles

When turning a tractor-trailer, why must you swing wide?

Reviewed by Jordan Morley, Editorial Lead at 247SimpleTests. Written by the 247SimpleTests Editorial Team from the official source material cited on every question.

Correct answer

Because the trailer's rear wheels off-track to the inside of the turn and may climb the curb or strike anything in the inside corner

  1. A Because the trailer's rear wheels off-track to the inside of the turn and may climb the curb or strike anything in the inside corner
  2. B Only when the trailer is empty
  3. C To impress other drivers
  4. D Only on left turns

Why this is the answer

Off-tracking is the geometric tendency of the trailer's rear wheels to follow a tighter path through a turn than the tractor. On a right turn, if you steer tight to the inside curb, the trailer's rear wheels will climb the curb or strike pedestrians and vehicles on the inside corner. The technique is to begin the turn from further out (without crossing into oncoming or adjacent lanes), aim to put the tractor's rear wheels close to the corner you are turning around, and let the trailer's wheels follow the tractor's wheels through the turn. Off-tracking is greater with longer trailers and tighter turns. Drivers must learn to feel where the rear of the trailer is at any moment during a turn, since it is invisible in the mirrors during much of the maneuver.
Source: FMCSA CDL Manual 6.1.3 Off-Tracking

Practice more questions

This question is from our CDL Practice Tests practice test. Take the full practice test to test your knowledge across all Driving Combination Vehicles and other topics.

Take the Combination Vehicles practice test →

About this topic: Driving Combination Vehicles

Off-tracking, jackknife risk, and rearward amplification mean a tractor-trailer behaves nothing like a single vehicle. Smooth inputs and conservative speed prevent the worst outcomes. This is one of 20 Combination Vehicles questions on driving combination vehicles, each with a full explanation on a single study page.

New to this exam? Our CDL exam guide explains the format, scoring, and how to prepare.

Related questions

Driving Combination Vehicles

Why is rearward amplification a danger in multi-trailer combinations?

 Driving Combination Vehicles

When backing a tractor with a single trailer, you should:

 Driving Combination Vehicles

What is a jackknife and what most commonly causes it?

 Driving Combination Vehicles

What is the proper speed adjustment for a tractor-trailer entering a curve?

State-specific guides

Need information for your state? Our state guides cover local requirements, fees, and what to expect on exam day.

California Texas Florida New York Pennsylvania Illinois Ohio Georgia

Recommended study materials

Study guide

CDL Study Guide (Trivium)

Complete prep for all CDL written tests: general knowledge, air brakes, combination vehicles, hazmat, and all endorsements. Includes full-length practice tests.

Check Price → Study guide

CDL Practice Tests & Flashcards (Accepted Inc.)

600+ practice questions covering every FMCSA knowledge area, plus 400 flashcards for endorsement prep.

Check Price → Study guide

Master the CDL Truck Driver's License (Arco)

Arco's classic CDL prep with in-depth FMCSA manual coverage, endorsement chapters, and scored practice exams.

Check Price →

As an Amazon Associate, CJ Affiliate, and AWIN publisher we earn from qualifying purchases. Links above are affiliate links. Full disclosure →