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General Knowledge CDL Practice Test

The General Knowledge exam is the foundation of every CDL. Every commercial driver — Class A, B, or C — must pass it before any endorsement is added. The test covers vehicle inspection, basic control, shifting, backing, communicating, distracted and aggressive driver awareness, night and adverse-condition driving, railroad-highway grade crossings, accident procedures, fires, alcohol and drug rules, hazardous materials awareness, fatigue management, and cargo securement basics.

Why this test exists

FMCSA requires General Knowledge competency under 49 CFR 383.111 because every CDL holder operates a heavy vehicle in mixed traffic where situational judgment, pre-trip discipline, and emergency response routinely separate a safe trip from a fatal one.

How to study this section

Read the FMCSA Model CDL Manual Section 2 cover to cover, then re-read it focused on numbers — speeds, distances, weights, and pressures. Use the practice questions in this category to drill those numeric thresholds until you can answer without hesitation.

65 practice questions

• Q1. What is the most frequent cause of crashes involving commercial motor vehicles?
• Q2. A complete pre-trip inspection of a commercial vehicle should take approximately how long?
• Q3. GVWR stands for:
• Q4. When you must back a tractor-trailer, you should:
• Q5. The proper hand position on the steering wheel is:
• Q6. Controlled braking on a CDL vehicle means:
• Q7. Stab braking means:
• Q8. The basic rule for safe following distance is one second per 10 feet of vehicle length under 40 mph,…
• Q9. You should turn off your engine retarder when:
• Q10. You should check your mirrors approximately every:
• Q11. Hydroplaning can begin at speeds as low as:
• Q12. Black ice is most likely to form:
• Q13. The three types of skids you must recognize are:
• Q14. Total stopping distance equals:
• Q15. At 55 mph, the average reaction distance is approximately:
• Q16. Approximate total stopping distance for a fully loaded tractor-trailer at 55 mph on dry pavement is:
• Q17. Under federal Hours of Service rules, the maximum driving time within a 14-hour on-duty window is:
• Q18. A 30-minute break is required after how many cumulative hours of driving?
• Q19. The 34-hour restart requires:
• Q20. A CDL holder is considered to be 'driving while intoxicated' at a blood alcohol concentration of:
• Q21. A first DUI conviction in a CDL vehicle results in disqualification for:
• Q22. A second DUI conviction in a CDL results in:
• Q23. Refusing a chemical alcohol test under federal CDL rules:
• Q24. Leaving the scene of an accident in a CDL vehicle results in:
• Q25. When required to stop at a railroad crossing, you must stop within:
• Q26. Vehicles always required to stop at every railroad crossing include:
• Q27. When approaching a railroad crossing, you should look both ways at least:
• Q28. The general rule for cargo tiedowns is at least one tiedown per:
• Q29. The aggregate working load limit of all tiedowns must equal at least:
• Q30. Headlights are required from:
• Q31. You must dim high beams to low beams when an oncoming vehicle is within:
• Q32. When driving in fog, you should:
• Q33. Tire chains must be carried or installed when:
• Q34. If your vehicle begins to hydroplane, you should:
• Q35. On wet roads, you should reduce speed by approximately:
• Q36. On packed snow, reduce speed by approximately:
• Q37. On icy pavement, you should:
• Q38. Class B fire extinguishers are designed for fires involving:
• Q39. When descending a long downgrade you should:
• Q40. Engine brakes (Jake brakes) on wet roads should be:
• Q41. Convex (curved) mirrors:
• Q42. A yellow center line on a roadway separates:
• Q43. The best response to an aggressive driver is to:
• Q44. Texting while operating a CMV is:
• Q45. The FMCSA Drug and Alcohol Clearinghouse is:
• Q46. A standard DOT drug screen tests for how many substances?
• Q47. Federal random drug testing pool minimum is:
• Q48. The Working Load Limit (WLL) of a tiedown chain assembly is:
• Q49. A driver who is not endorsed for hazmat must still:
• Q50. Your medical examiner's certificate generally must be renewed at least every:
• Q51. Off-tracking refers to:
• Q52. When making a right turn at an intersection, you should:
• Q53. Reflective triangles after a stop on the road must be set out within:
• Q54. On a divided highway, the rear-most reflective triangle should be placed:
• Q55. The hand-held microphone (CB) or cell phone use rule for CDL drivers is:
• Q56. A perception distance is:
• Q57. Black smoke from your exhaust generally indicates:
• Q58. The first thing to do at the scene of an accident is:
• Q59. A vehicle equipped with anti-lock brakes (ABS):
• Q60. When checking tires during a pre-trip, minimum tread depth on steer tires is:
• Q61. Minimum tread depth on non-steer tires is:
• Q62. The CDL must be carried by the driver:
• Q63. A driver discovering a leak from their fuel tank during a trip should:
• Q64. The most common reason for being placed out of service at a roadside inspection is:
• Q65. When parking on a level surface, you should:

State-specific resources

Each U.S. state administers the CDL knowledge test through its own DMV. The federal questions are the same; the test scheduling, fees, and identification requirements vary. Start with your state's overview:

See all 50 states →