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CO CDL Double/Triple Trailers Marathon

19 min

Ready for something really challenging? This Colorado CDL Double/Triple Trailers Marathon is a super-challenging practice test that contains a mix of all 101 questions that we have available for this CO endorsement. If you select a wrong answer, we’ll remember that question and will display it to you again at the end of the exam until you’ve answered that question correctly. In other words, the Marathon will cycle through your missed questions until you answer each one correctly. You must make a 100% to pass. We suggest you attempt this one after you have practiced the state’s “regular” tests, but before the “Exam”. Delivers some serious studying power! Do your best to complete this mega test!

Commercial Driver's License
Based on the official CO CDL HandbookHandbook‑based (2025) + exam‑taker feedback
This test is a Premium member exclusive. You'll get

All 650 exam-like questions specific to Colorado

Interactive learning with AI personal tutor

Unique 360° Virtual Road Simulations

Get your money back if you don’t pass

Accuracy & authorship

Steven Litvintchouk, M.S., Chief Educational Researcher at Driving-Tests.org

Reviewed for legal and handbook accuracy:

Steven Litvintchouk

M.S., Chief Educational Researcher (ACES member)

Last verified for accuracy on

Andrei Zakhareuski, Co-founder & CEO at Driving-Tests.org

Test design and learning experience oversight:

Andrei Zakhareuski

Co-founder & CEO, Driving-Tests.org

Questions are created and maintained by the Driving-Tests.org content team following our multi-layer editorial process and updated whenever the Colorado DMV changes its handbook or website information.

Official sources we check: Colorado CDL Handbook (2025 edition), Colorado DMV website

How to use this practice test

  1. Start here. One of 4 free Colorado tests. ~19 min. Read explanations as you go.
  2. Cover more ground. All tests have different questions - no repeats.
  3. Finish strong. Try the Exam Simulator for a full-length run.

Why this works

  • Exam-like questions from the current handbook + real test-taker patterns. Explanations cite the manual.
  • AI Assistant explains tricky items in plain language.
  • Performance Insights show your weak topics and what to study next.
  • Challenge Bank™ saves your mistakes for targeted practice.

Actual DMV permit test: What to expect?

The Colorado permit test has 20 questions. You must get 16 correct (80%) to pass.
  • Where: Any Colorado DMV office (find locations)
  • Bring: ID + SSN + residency proof + permit/license fee (see checklist)
  • If you fail: Retake next business day / 24 hours.
  • Commonly missed: headlight usage and when to turn them on, railroad crossing procedures.
  • Ready to schedule? Book your CO DMV appointment

We know what it takes to pass. And we’ve got the proof.

Driver’s Ed is - nobody wants to set foot inside the DMV. That’s why millions of learners trust us for simple, visual, effective prep.

An official & trusted partner in driver education

We are an officially recognized FMCSA Entry-Level Driver Training provider and a proud partner to over 2,500 libraries. We work with safety organizations like GHSA and the National Safety Council to help create safer roads for everyone.

A smarter way to study

Challenge Bank™

Our trademarked system automatically saves questions you miss, creating personalized tests that target your weak spots until you’ve mastered the material.

AI-powered feedback

Get smarter as you study. Our new AI-powered feedback provides detailed, question-level insights to help you understand the why behind each answer.

Interactive handbook

Go beyond the boring black-and-white manual. Our interactive handbook lets you read, listen with an MP3 audio version, or even chat with it to find the information you need, faster.