Vehicle Inspection
The Core Idea
Inspection questions test the seven-step walk-around and your ability to spot defects that make a vehicle unsafe. The exam expects you to know what to check and why.
Concepts You Must Know
- Pre-trip inspection covers: engine compartment (fluid levels, belts, hoses, leaks), lights and reflectors, tires and wheels, brake system, suspension, coupling devices, and emergency equipment.
- Tire checks: tread depth (at least 4/32 inch on front steer tires, 2/32 inch on other tires), sidewall condition, and proper inflation. Look for cuts, bulges, and exposed cords.
- Brake checks include slack adjuster travel, brake pad/liner thickness, and air leaks.
- Lights: check headlights, turn signals, brake lights, clearance lights, and reflectors. A burned-out light is a defect.
- Emergency equipment: fire extinguisher, triangles, and spare fuses where required.
- During-trip inspection: check cargo securement and look for leaks or shifting loads.
Traps to Watch
The biggest trap is the tread depth numbers - 4/32 for steer tires versus 2/32 for others. Another is confusing a pre-trip check with a during-trip check. Questions may also describe a defect and ask whether the vehicle can be driven - the answer is usually no if the defect affects safety.
Rule of Thumb
"4 on the steer, 2 on the rear." If a tire on the steering axle is below 4/32 inch, it is out of service.