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Maryland CDL practice

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Maryland CDL: Vehicle inspection and developing defects

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Question 1 of 16
  1. 1. An interstate truck's front tire has 3/32 inch of tread in a major groove. Does it meet the federal minimum for that position?
  2. 2. For a truck subject to federal tire rules, what minimum major-groove tread depth applies to a tire that is not on a front wheel?
  3. 3. A bus subject to federal equipment rules has a retreaded front tire with deep, undamaged tread. Is the tread depth enough to make that installation acceptable?
  4. 4. On a commercial vehicle subject to federal tire rules, a sidewall cut exposes the tire's reinforcing material. What should the driver do?
  5. 5. During a walk-around, you notice new rust streaks extending from wheel nuts. What do they suggest?
  6. 6. Two tires in a dual assembly are touching each other. How should you treat this finding?
  7. 7. You find grease on a truck's brake lining during inspection. What is the appropriate response?
  8. 8. Why is a cracked spring hanger more serious than a comfort problem?
  9. 9. A driver notices an exhaust leak beneath the sleeper area. Why must it be addressed?
  10. 10. Before climbing into a parked truck, which observation deserves investigation?
  11. 11. A driver checks the same vehicle daily. What approach best reduces overlooked inspection items?
  12. 12. A loose tool bag is resting where it could slide under the pedals. When should you secure it?
  13. 13. During the handbook's stationary hydraulic-brake check, the pedal keeps moving down while firm pressure is held. What does that indicate?
  14. 14. A parking brake fails to hold during its controlled inspection test. What should happen next?
  15. 15. In a safe low-speed brake check, the truck pulls noticeably to one side. What is the best conclusion?
  16. 16. After a normal pre-trip inspection, the coolant gauge starts rising unusually during the trip. What should the driver do?
Review all 16 questions with answers

  1. An interstate truck's front tire has 3/32 inch of tread in a major groove. Does it meet the federal minimum for that position?

    Correct answer: No. A front tire needs at least 4/32 inch.

    For a truck, truck tractor or bus subject to this rule, front-wheel tires need at least 4/32 inch in a major tread groove, measured away from tie bars, humps and fillets. A 3/32-inch reading is below that minimum.

    Source: 49 CFR 393.75(b); eCFR title 49 displayed current through September 11, 2026; reviewed September 15, 2026. ↗

  2. For a truck subject to federal tire rules, what minimum major-groove tread depth applies to a tire that is not on a front wheel?

    Correct answer: 2/32 inch.

    The federal minimum is 2/32 inch for these other tires. The separate front-wheel requirement is 4/32 inch. Measure in a major groove, away from raised tie bars, humps and fillets.

    Source: 49 CFR 393.75(c); eCFR title 49 displayed current through September 11, 2026; reviewed September 15, 2026. ↗

  3. A bus subject to federal equipment rules has a retreaded front tire with deep, undamaged tread. Is the tread depth enough to make that installation acceptable?

    Correct answer: No. Retreaded tires are prohibited on the front wheels of the bus.

    Federal rules prohibit regrooved, recapped and retreaded tires on the front wheels of a bus. Adequate tread depth does not remove that position-specific restriction; this is not a ban on every rear tire.

    Source: 49 CFR 393.75(d); eCFR title 49 displayed current through September 11, 2026; reviewed September 15, 2026. ↗

  4. On a commercial vehicle subject to federal tire rules, a sidewall cut exposes the tire's reinforcing material. What should the driver do?

    Correct answer: Have the unsafe tire corrected before operating the vehicle.

    Exposed body-ply or belt material is a prohibited tire condition, whether exposed through the tread or sidewall. Tread depth and the presence of a neighboring tire do not make that tire safe.

    Source: 49 CFR 393.75(a)(1), (a)(4); eCFR title 49 displayed current through September 11, 2026; reviewed September 15, 2026. ↗

  5. During a walk-around, you notice new rust streaks extending from wheel nuts. What do they suggest?

    Correct answer: The nuts may be loose and their tightness needs checking.

    Rust trails can indicate movement at a wheel nut. Check the assembly rather than dismissing the streaks as cosmetic. The handbook also calls for a tightness recheck after a wheel has recently been changed.

    Source: Maryland Commercial Driver’s License Manual, DL-151 (02/26), February 2026; Section 2; 2.1.3 Wheel and Rim Problems; physical PDF page 38 (printed 38); public mirror of the Maryland manual; reviewed September 15, 2026. ↗

  6. Two tires in a dual assembly are touching each other. How should you treat this finding?

    Correct answer: As a tire defect to resolve before the vehicle is driven.

    Dual tires should not rub against each other or vehicle components. Matching size and apparently good tread do not cancel the need to investigate contact and correct the unsafe condition.

    Source: Maryland Commercial Driver’s License Manual, DL-151 (02/26), February 2026; Section 2; 2.1.3 Tire Problems; physical PDF page 38 (printed 38); public mirror of the Maryland manual; reviewed September 15, 2026. ↗

  7. You find grease on a truck's brake lining during inspection. What is the appropriate response?

    Correct answer: Have the brake defect corrected before starting the trip.

    Oil, grease or brake fluid on friction material is a brake defect. A sound drum does not make contaminated lining acceptable, and the parking brake is not a substitute for a safe service-brake system.

    Source: Maryland Commercial Driver’s License Manual, DL-151 (02/26), February 2026; Section 2; 2.1.3 Bad Brake Drums or Shoes; physical PDF page 38 (printed 38); public mirror of the Maryland manual; reviewed September 15, 2026. ↗

  8. Why is a cracked spring hanger more serious than a comfort problem?

    Correct answer: A cracked hanger can let the axle shift and must be corrected.

    The suspension supports the vehicle and load while keeping axles correctly positioned. Damaged hangers or related mounting parts can threaten control and require attention, even before several spring leaves have failed.

    Source: Maryland Commercial Driver’s License Manual, DL-151 (02/26), February 2026; Section 2; 2.1.3 Suspension System Defects, pages 39–40; physical PDF page 40 (printed 40); public mirror of the Maryland manual; reviewed September 15, 2026. ↗

  9. A driver notices an exhaust leak beneath the sleeper area. Why must it be addressed?

    Correct answer: Poisonous exhaust can enter the cab or sleeper.

    A damaged exhaust system can let poisonous fumes into occupied spaces. Check leaking or unsecured exhaust components and have the defect corrected; opening a window is not a repair.

    Source: Maryland Commercial Driver’s License Manual, DL-151 (02/26), February 2026; Section 2; 2.1.3 Exhaust System Defects; physical PDF page 41 (printed 41); public mirror of the Maryland manual; reviewed September 15, 2026. ↗

  10. Before climbing into a parked truck, which observation deserves investigation?

    Correct answer: A fresh fluid puddle under the engine area.

    The approach inspection looks for clues such as fresh leaks, damage or an unusual lean, as well as people and obstacles around the vehicle. Investigate a fresh puddle instead of discovering the problem after departure.

    Source: Maryland Commercial Driver’s License Manual, DL-151 (02/26), February 2026; Section 2; 2.1.5 Method of Inspection; approaching the vehicle; physical PDF page 42 (printed 42); public mirror of the Maryland manual; reviewed September 15, 2026. ↗

  11. A driver checks the same vehicle daily. What approach best reduces overlooked inspection items?

    Correct answer: Use a consistent inspection routine on each trip.

    A repeatable method helps prevent omissions. Familiarity with a vehicle or a trouble-free previous trip does not show that its current condition is safe.

    Source: Maryland Commercial Driver’s License Manual, DL-151 (02/26), February 2026; Section 2; 2.1.5 Method of Inspection; physical PDF page 42 (printed 42); public mirror of the Maryland manual; reviewed September 15, 2026. ↗

  12. A loose tool bag is resting where it could slide under the pedals. When should you secure it?

    Correct answer: Before moving, so it cannot obstruct the controls.

    Loose cab objects can interfere with driving controls or strike occupants in a crash. Secure them before driving rather than relying on their current position.

    Source: Maryland Commercial Driver’s License Manual, DL-151 (02/26), February 2026; Section 2; 2.1.5 Step 6; secure loose cab items; physical PDF page 50 (printed 50); public mirror of the Maryland manual; reviewed September 15, 2026. ↗

  13. During the handbook's stationary hydraulic-brake check, the pedal keeps moving down while firm pressure is held. What does that indicate?

    Correct answer: A possible leak or other fault that needs repair before driving.

    A pedal that does not hold its position during this check can indicate a hydraulic leak or another brake problem. Get it corrected before driving. Air-brake vehicles require their own different checks.

    Source: Maryland Commercial Driver’s License Manual, DL-151 (02/26), February 2026; Section 2; 2.1.5 Step 7; Test for hydraulic leaks; physical PDF page 50 (printed 50); public mirror of the Maryland manual; reviewed September 15, 2026. ↗

  14. A parking brake fails to hold during its controlled inspection test. What should happen next?

    Correct answer: Have the faulty parking brake repaired before operation.

    The parking brake must hold the vehicle as intended. A failed test is a defect to fix, not a reason to substitute an improvised parking routine.

    Source: Maryland Commercial Driver’s License Manual, DL-151 (02/26), February 2026; Section 2; 2.1.5 Test Parking Brake(s), continued; physical PDF page 51 (printed 51); public mirror of the Maryland manual; reviewed September 15, 2026. ↗

  15. In a safe low-speed brake check, the truck pulls noticeably to one side. What is the best conclusion?

    Correct answer: A brake or related safety problem needs investigation.

    Pulling, unusual pedal feel or delayed stopping action can signal trouble. Resolve an unsafe condition before the trip instead of treating steering compensation as a repair.

    Source: Maryland Commercial Driver’s License Manual, DL-151 (02/26), February 2026; Section 2; 2.1.5 Test the Service Brake Stopping Action; physical PDF page 51 (printed 51); public mirror of the Maryland manual; reviewed September 15, 2026. ↗

  16. After a normal pre-trip inspection, the coolant gauge starts rising unusually during the trip. What should the driver do?

    Correct answer: Respond to the warning and investigate at a safe stopping place.

    Pre-trip inspection is not the end of monitoring. Watch instruments and use sight, sound, smell and feel for developing problems; do not let a reassuring earlier check override a new warning.

    Source: Maryland Commercial Driver’s License Manual, DL-151 (02/26), February 2026; Section 2; 2.1.6 Inspection During a Trip; physical PDF page 51 (printed 51); public mirror of the Maryland manual; reviewed September 15, 2026. ↗

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Question reference: md-cdl-general-001

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Home / Maryland / CDL

Maryland CDL practice

744 questions: 176 general knowledge and cargo, 48 air brakes, 48 combination vehicles, 40 passenger, 24 tank, 24 doubles/triples, 64 school-bus, 80 hazardous-material, 96 licensing, 80 inspection/skills and 64 operating/recordkeeping questions. Start below or choose a focused test.

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What these tests cover

The eleven general-knowledge sets and six equipment sets contain 16 questions each. Passenger practice has four 10-question sets; tank and doubles/triples each have two 12-question sets. School-bus practice has four 16-question sets; hazardous materials and skills preparation each have five, and licensing has six. Operating responsibilities, CDL exclusions, military skills waivers and IFTA records/credentials have four 16-question sets. Sets do not repeat records. General random practice draws from 176 questions; other subjects use their separate question sets. Each answer includes an explanation based on the relevant Maryland manual section, state requirement or federal rule.

This question set covers driving basics, cargo, air brakes, combinations, passenger vehicles, tanks, doubles/triples, school buses, hazardous materials, licensing responsibilities, written skills preparation, fitness for duty, CDL exclusions, military waivers and trip/fuel records. It is not a substitute for complete CDL training. Written practice does not replace required ELDT, employer hazmat training, security screening or hands-on skills training. Maryland does not permit triple-trailer highway operation; the T endorsement does not override that restriction. Read all required manual sections, check current licensing and training requirements, and prepare hands-on for the skills test. These are original study scenarios, not official exam questions.

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