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In Oklahoma City, I-35 (Texas to Minnesota), I-40 (California to North Carolina), and I-44 (Texas to Missouri) meet to form “America’s Crossroads,” one of the nation’s most important highway junctions. This junction has helped make Oklahoma a central logistics hub. The state’s logistics and intermodal (rail-to-truck) sectors make great use of double-trailer and triple-trailer trucks. (Triple trailers are legal on the state’s turnpikes.) Triple-trailer trucks are used by parcel and Less-Than-Truckload (LTL) carriers.
Oklahoma is also a major regional distribution center for retail chains, such as Walmart. These companies operate doubles to transport products to multiple stores efficiently. The oil and gas industry uses doubles to transport crude oil, drilling equipment, and fuel. The agriculture industry uses double trailers to haul feed, fertilizer, grain, and livestock. Finally, the manufacturing industry uses doubles to transport raw materials, components, and finished goods.
Would you like to pull doubles or triples in one of these economic sectors? You must hold a Class A CDL, be qualified to operate air brakes, and obtain a Double/Triple (T) endorsement on your Class A CDL.
M.S., Chief Educational Researcher (ACES member)
Last verified for accuracy on
To obtain the Double/Triple endorsement, you must pass the official Double/Triple knowledge test. This test covers such topics as safe handling, air brakes on doubles and triples, coupling and uncoupling, pre-trip inspections, rollovers, and trailer sway. (Note that no special skills test is required for this endorsement.)
This knowledge test is based on the official Oklahoma CDL manual (Oklahoma CDL Handbook 2026), especially Chapter 7: Doubles and Triples. However, you may have noticed this manual isn’t easy to learn. We can help you pass this knowledge test on your first try.
This is the first of our Oklahoma Doubles and Triples Endorsement Practice Tests. It’s based on the official CDL manual, like the Double/Triple knowledge test. It’s up to date as of January 2026. The 20 multiple-choice practice questions and answers on this practice test deal with air lines, converter dollies, coupling, following distance, rearward amplification, rollovers, and other topics.
Our AI Assistant can help you figure out the answer to any practice question. You can ask it to give you a hint or rephrase the question. You can also ask your own questions. If you still miss the question, the AI Assistant will immediately give you the correct answer and an accompanying explanation.
This practice test isn’t timed; take all the time you need to learn and master the material covered by this practice test. You can retake this practice test as often as you wish. Each time, the order of the questions will be randomized.
Driver’s Ed is - nobody wants to set foot inside the DPS. That’s why millions of learners trust us for simple, visual, effective prep.
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.
Our trademarked system automatically saves questions you miss, creating personalized tests that target your weak spots until you’ve mastered the material.
Get smarter as you study. Our new AI-powered feedback provides detailed, question-level insights to help you understand the why behind each answer.
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.
We build our practice questions from the current 2026 OK Driver Handbook and refine them using patterns recent test‑takers report.
Driver handbook • Knowledge‑test/permit overview • Fees & ID requirements • Office/appointment info
We mirror recurring themes (e.g., right‑of‑way traps, sign look‑alikes) and use similar distractors and wording styles.
We don’t collect or publish actual test items and we’re not affiliated with DPS.
