CDL Pre-Trip Inspection Practice
The pre-trip is the part of the CDL exam most people fail, because it is spoken out loud from memory in front of an examiner. Learn the route around the truck as a fixed sequence and the specs that go with each stop, and it stops being memorization and starts being an inspection.
Written and reviewed by Christopher Scott Sneed, 30+ year diesel technician, founder of Blue Collar Empire.
What this section covers
- Engine compartment: belts, hoses, leaks, fluid levels, steering components
- Cab check: gauges, lights, horn, wipers, mirrors, safety equipment
- Lights and reflectors, front to rear
- Tires, wheels, and rims — including the 4/32 steer and 2/32 other tread minimums
- Suspension, brakes, and frame defects that put a truck out of service
- Coupling area and cargo securement
- The air brake test: static leakage, applied leakage, low-air warning, spring brake pop-out
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Minimum tread depth on steer tires is:
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6 practice questions with explanations
1. Minimum tread depth on steer tires is:
- A. 2/32 inch
- B. 4/32 inch — correct
- C. 6/32 inch
- D. 8/32 inch
Why: 4/32 in on steer tires; 2/32 in on all others (FMCSA).
2. You should check for oil, coolant, and fuel leaks:
- A. Only if the truck is new
- B. Every pre-trip and en-route stop — correct
- C. Weekly
- D. Monthly
Why: Any leak found on a pre-trip is a defect and must be addressed.
3. During pre-trip, the steering wheel should have no more free play than:
- A. 10 degrees / 2 inches on a 20-inch wheel — correct
- B. 45 degrees
- C. 1 full turn
- D. There is no limit
Why: More than about 10° of play indicates worn steering components.
4. Which is NOT a required light check?
- A. Headlights (low/high)
- B. Turn signals
- C. Cargo interior lights — correct
- D. Brake lights
Why: Interior cargo lights aren't part of a required exterior lighting inspection.
5. Cracked or broken leaf springs are:
- A. Acceptable if minor
- B. An immediate out-of-service defect — correct
- C. Only a concern loaded
- D. Only a concern in winter
Why: A broken main spring leaf is an out-of-service defect.
6. The 3 points of contact rule means:
- A. Steering wheel, shifter, mirror
- B. Two hands and one foot, or two feet and one hand, when climbing — correct
- C. Three tire contact patches
- D. Three inspection stops
Why: Always maintain three points of contact getting in and out of the cab and on the trailer.
How to study this section
- Say it out loud while you walk the truck. The examiner scores what you say, not what you look at.
- Group the specs: 4/32 steer tread, 2/32 everything else, 10 degrees steering play, 60 psi low-air warning.
- Any leak, crack, or missing fastener you find is a defect — name it and say why it matters.
- Three points of contact, every time you climb up or down.
Frequently asked questions
- What is included in the CDL pre-trip inspection?
- A systematic walk-around covering the engine compartment, cab and safety equipment, lights, tires and wheels, suspension and brakes, the coupling area on a combination unit, cargo securement, and the air brake test series.
- How long does the pre-trip inspection test take?
- Usually 20 to 40 minutes depending on the state and whether you are testing on a combination vehicle.
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