Doubles / Triples Practice Test
The T endorsement is required to pull combinations consisting of more than one trailer. The test focuses on coupling and uncoupling converter dollies, pintle hooks and safety chains, the proper order of trailers (heaviest behind the tractor), inspection of the additional articulation points, and control techniques to prevent the rear trailer from rolling over because of the crack-the-whip effect. Doubles and triples are governed by both federal STAA limits and state-specific routing rules.
How to use this practice bank
Read each question carefully before checking the answer. Most CDL questions are not designed to trick you, but they do test whether you know the specific rule — not just what feels safe. After reading the explanation, try to restate the rule in your own words; if you can, you've internalized it. If you can't, look up the corresponding chapter of your state's CDL handbook before moving on.
Pass scores vary slightly by state, but most jurisdictions require at least 80% correct on each knowledge exam. With 30 questions in this bank you have substantially more practice material than any single sitting of the real exam, which typically contains 20 to 50 questions per endorsement.
All 30 questions in this bank
- #1The trailer most likely to roll over in a doubles or triples combination is:
- #2When uncoupling a converter dolly from a rear trailer, you should:
- #3When inspecting a converter dolly, look for:
- #4The proper way to couple a second trailer is to:
- #5A driver of a doubles or triples combination should plan ahead for stops because:
- #6Off-tracking in a triple combination is:
- #7The pintle hook on a converter dolly:
- #8Safety chains on a converter dolly:
- #9When pulling doubles or triples on a slippery road, the driver should:
- #10A driver checks the trailer brakes between two trailers by:
- #11The longer the combination of vehicles, the:
- #12Drivers of doubles and triples must avoid:
- #13When parking a doubles or triples combination, the driver should:
- #14The proper coupling order for a doubles set is:
- #15When inspecting the lower fifth wheel of a converter dolly, you should look at:
- #16When uncoupling the rear trailer of a doubles set, the driver should:
- #17When unhooking a converter dolly from the trailer ahead, you should:
- #18Trailers in a triples combination should be inspected:
- #19Doubles and triples are restricted in:
- #20Empty trailers in a doubles or triples set may bounce or sway because:
- #21The combined length of a doubles or triples is greater than a single trailer, so:
- #22When meeting an oncoming vehicle on a narrow road with a doubles or triples set, the driver should:
- #23The dolly's air supply line is connected to:
- #24A driver discovers an air leak between the first and second trailer. The driver should:
- #25A converter dolly may have either:
- #26You should always inspect doubles and triples trailers for:
- #27The handling of doubles and triples is most affected by:
- #28When backing a converter dolly without a trailer attached, the dolly:
- #29A 'rocky-mountain double' is a combination of:
- #30A 'turnpike double' is:
About the Doubles / Triples exam
The Doubles / Triples knowledge test is a multiple-choice exam administered at every state CDL testing site. The questions on this page are seeded from the AAMVA Commercial Driver License Manual — the same source that state agencies use when writing their official questions — and from the corresponding sections of Title 49 of the Code of Federal Regulations. Real test questions are randomly selected from a much larger pool, so practice covers the rules and concepts rather than the wording of any one item.
The most efficient way to study is to work through this bank twice. The first pass identifies the rules you do not yet know; the second pass confirms recall. Drivers who have studied for years rarely miss a question, but newcomers should expect to need a week or more of repeated reading and quizzing before sitting the real exam. Combine this site with your state's printed CDL handbook for the most complete preparation.