CDL Pre-Trip Inspection: A Simple Walkthrough
Updated June 2026
Free CDL pre-trip inspection practice test — no sign-up.
The pre-trip inspection catches problems before they put you (and everyone around you) at risk — and it's a required part of the CDL skills test. Here's the flow, in the order most examiners want it.
1. Engine compartment (hood up)
- Oil, coolant and power-steering fluid levels.
- Belts and hoses — no cracks, fraying or leaks.
- No puddles or drips under the engine.
- Wiring and the alternator/water pump mounted securely.
2. In the cab (engine running)
- Gauges build and hold air; the low-air warning works and the spring brakes set at the right pressure.
- Lights, wipers, horn, mirrors and the seat belt.
- Do the brake checks: air build-up, leak-down, low-air warning, and that the parking brake and service brake hold.
3. The walk-around
Work your way around the truck and trailer, checking at each point:
- Tires: proper inflation, tread depth (4/32" steer, 2/32" others), no cuts or bulges.
- Wheels: lug nuts tight (no rust trails), no oil/grease around the hubs (wheel seals).
- Brakes: slack adjusters, brake chambers, and drums/linings.
- Suspension: springs, shocks, mounts — nothing cracked, shifted or missing.
- Lights & reflectors: clean and working all the way around.
- Coupling: fifth wheel locked, no gap, kingpin secure, air lines and cords connected and not dragging.
- Frame, fuel tank, exhaust: secure, no leaks.
Tip for the test
Examiners want you to point at and name each part and say what you're looking for ("I'm checking this tire for proper inflation, adequate tread, and no cuts or bulges"). Practice out loud. The free practice test below drills the same knowledge.
Free CDL pre-trip inspection practice test — no sign-up.
Frequently asked questions
How long does a pre-trip inspection take?
A thorough pre-trip usually takes 15–30 minutes. On the CDL test, plan for a methodical walk-through — rushing causes missed points.
Do I do a pre-trip every day?
Yes — before every trip, plus a post-trip inspection at the end. It's both a safety habit and a legal requirement.