A proper pre-trip inspection is your first line of defense against breakdowns, DOT violations, and out-of-service orders. It is also a federal requirement under FMCSA rules, and it is part of the CDL skills test for a reason.
Use this checklist before every trip. It is organized the way an inspector — and a smart driver — works through a rig: engine compartment first, then a walk-around, the coupling system, and finally the in-cab checks. Print it, keep a copy in the cab, and work top to bottom every time.
Engine Compartment (Engine Off)
- Engine oil level and condition
- Coolant level and hoses (no leaks, soft spots, or chafing)
- Power steering fluid level and lines
- Belts — no fraying, proper tension
- Water pump and alternator mountings secure
- Leaks under the engine (oil, coolant, fuel)
- Air compressor and lines secure
- Wiring — no cracked, frayed, or loose connections
Exterior Walk-Around
- Tires — tread depth, even wear, proper inflation, no cuts or bulges
- Steer tires at least 4/32" tread; others at least 2/32"
- Wheels and rims — no cracks, all lug nuts present and tight
- No oil or grease leaks at hubs (check seals)
- Brake drums/rotors and visible brake components
- Suspension — springs, hangers, U-bolts, shocks, airbags
- Frame and crossmembers — no cracks or bends
- Lights and reflectors — all clean, working, correct color
- Mirrors clean and properly adjusted
- Fuel tanks secure, caps tight, no leaks
- Exhaust system secure, no leaks
- Mud flaps present and secure
Coupling System (Tractor-Trailer)
- Fifth wheel secure, no cracks or excessive play
- Kingpin and apron in good condition
- Locking jaws fully closed around the kingpin
- Release arm properly seated and safety latch engaged
- No gap between trailer apron and fifth wheel
- Air lines and electrical line secure, no leaks, no chafing
- Landing gear fully raised, crank handle secured
In-Cab & Brake Checks
- Gauges and warning lights function on startup
- Wipers, washers, heater, and defroster work
- Horn (city and air) works
- Seat belt secure and not frayed
- Steering play within limits
- Air pressure builds to governor cutout (around 120 psi)
- Low-air warning activates before pressure drops below 60 psi
- Air pressure leak-down test within limits (engine off, brakes applied)
- Parking brake holds against a gentle pull
- Service brake stops the vehicle and does not pull to one side
- Required paperwork, registration, and emergency equipment on board
Find a defect you cannot safely fix yourself? Do not roll. Call Weldon's Truck & Trailer at (334) 759-7020 — we will come to you anywhere within our 200-mile service area.
Frequently Asked Questions
How long should a DOT pre-trip inspection take?
A thorough pre-trip inspection typically takes 15 to 30 minutes. Rushing it is the most common reason drivers miss a defect that later becomes a roadside breakdown or an out-of-service violation.
What is the minimum legal tread depth for commercial tires?
Federal rules require at least 4/32 inch of tread on steer tires and at least 2/32 inch on all other tires. Replace tires before they reach these limits to stay safe and compliant.
What happens if I find a defect during my pre-trip?
If the defect affects safe operation, the vehicle should not be driven until it is repaired. Document it, and call a mobile repair service like Weldon's if you cannot fix it yourself.
Is a pre-trip inspection legally required?
Yes. FMCSA regulations require drivers to be satisfied the vehicle is in safe operating condition before driving, and to review the last driver vehicle inspection report. A documented pre-trip protects you in an audit or after an incident.