Driver guide · 11 steps · about 30 minutes at the truck
The pre-trip inspection, step by step
Every trip starts with the same walk around the truck. Scroll and the drawing follows you: it opens the hood for the fluids, zooms to the steer tire, switches on the lamps and runs the air brake check on the gauges. The order follows the seven-step method in the state CDL manuals, and each step names the federal rule behind it.
Written for tractor-trailers with air brakes. A practical guide, not legal advice; always follow the truck maker's manual and your company's procedure.
The walk-around, step by step
01 Before you touch anything
Walk up and read the whole truck
Approach from a distance and look at the rig as one thing. A truck that leans, drips or sits wrong tells you where to look first.
- Truck sits level: no leaning to one side, no sagging spring
- Fresh fluid under the engine, axles or fuel tank: oil, coolant, grease or fuel
- New body damage since the last trip
- Last vehicle inspection report: if it listed defects, the repairs must be signed off before you drive
49 CFR 396.13: the driver must be satisfied the vehicle is safe and review the last inspection report
02 Engine compartment
Open the hood
With the parking brake set and the wheels chocked, tilt the hood and check every fluid and belt before the engine runs.
- Engine oil on the dipstick between the add and full marks
- Coolant above the low mark in the sight glass or reservoir
- Power steering fluid at the right level, no leaking hoses
- Belts snug, not cracked or frayed, with about half to three quarters of an inch of play at the center
- No wet spots, chafed wiring or loose hoses
CDL manual step 2: engine compartment check
03 Start the engine, inside the cab
Climb in and read the gauges
Make sure the parking brake is on and the transmission is in neutral or park, start the engine and watch the gauges come up.
- Oil pressure comes up to normal within seconds of starting
- Air pressure builds; the low-air warning goes out as pressure climbs
- Voltmeter or ammeter shows the alternator charging
- Coolant temperature starts to rise toward normal
- Horn, wipers, washers, heater and defroster all work; mirrors are clean and set
- Emergency equipment on board: a charged fire extinguisher, three reflective warning triangles, spare fuses unless the truck uses circuit breakers
49 CFR 392.7 (horn, wipers, mirrors) and 393.95 (emergency equipment)
04 Engine off, lights on
Turn on every light, then walk around
Shut the engine down, take the key with you, switch on the headlights and four-way flashers, and step out to check the lamps.
- Low beams and high beams on both sides
- Four-way flashers front and rear
- Amber clearance and marker lamps along the cab and the front of the trailer
- Red clearance, marker and tail lamps at the rear
- Reflectors and conspicuity tape clean and in place
49 CFR 392.7: lighting devices and reflectors must work before you drive
05 Walk-around: tires and wheels
Tires, wheels and rims
Start at the driver's side steer tire and work down every axle. Steer tires carry the tighter limit, so they go first.
- Tread depth at least 4/32 of an inch on steer tires and 2/32 on every other tire
- Pressure checked with a gauge against the tire maker's number, not by thumping
- No cuts, bulges, exposed cord or sidewall damage; duals not touching each other
- Lug nuts all there, none loose; rust trails around a nut usually mean it has been moving
- Rims not cracked or bent; hub oil seals not leaking
49 CFR 393.75 (tire tread depth) and 392.7 (tires, wheels and rims)
06 Walk-around: brakes and suspension
Under the truck at every axle
At each wheel position look at the brake parts and the springs that carry the load.
- Brake chambers and air hoses not cracked, cut or leaking
- Slack adjusters: pulled by hand, a pushrod that moves more than about an inch needs adjustment
- Brake drums or rotors not cracked; linings not worn thin or soaked with oil
- Leaf springs not cracked, shifted or missing; U-bolts and spring hangers tight
- Shock absorbers not leaking; air bags (on air ride) not leaking or flat
49 CFR 392.7: service brakes and parking brake must be in good working order
07 Walk-around: coupling
Fifth wheel, kingpin and air lines
Where the tractor meets the trailer, look, then confirm the lock. This is where a trailer comes loose on the road.
- Locking jaws closed around the kingpin shank, not the head; no gap between the fifth wheel plate and the trailer apron
- Release arm in the locked position, safety latch engaged
- Fifth wheel mounted solid to the frame, slider locked
- Air lines (service and emergency) and the electrical cord connected, not tangled, chafed or dragging
- Landing gear fully raised and the crank handle secured
49 CFR 392.7: coupling devices must be in good working order
08 Walk-around: trailer and rear
Down the trailer to the doors
Walk the full length of the trailer and finish at the rear.
- Frame rails and crossmembers not cracked or bent; floor not broken through
- Doors closed and latched, hinges and seals in place, cargo secured
- Rear impact guard (the underride bar) straight and not cracked
- Mud flaps and splash guards in place
- Tail lamps, brake lamps, turn signals and reflectors clean and intact
CDL manual step 5: walk-around inspection of the trailer
09 Signal lights
Check the turn and brake lamps
Back in the cab, turn off the headlights and flashers, switch on the left turn signal and walk to check it front and rear. Then the right.
- Left turn signal works at the front, side and rear
- Right turn signal works at the front, side and rear
- Brake lamps come on at the rear when the service brake is applied (use a helper or a brake-light tester)
CDL manual step 6: check signal lights
10 Start the engine, test the brakes
Air brake check
With the engine running and wheels chocked, run the air system through its test. Numbers below are the ones in the CDL manual for a combination vehicle.
- Air builds from 85 to 100 psi within about 45 seconds (dual air system)
- Governor cuts out around 125 psi and cuts back in around 100 psi
- With brakes released and engine off, air loss under 3 psi in one minute; with the brakes held on, under 4 psi in one minute after the first drop
- Low-air warning comes on at or before 60 psi as you fan the pressure down
- Tractor protection valve and spring brakes pop out between about 20 and 45 psi
- Parking brake holds against a gentle pull in low gear; service brake stops the truck straight at about 5 mph
49 CFR 392.7 (service and parking brakes) and the CDL manual air brake check
11 Paperwork
Sign off, then drive
A defect you find is a defect you report. Fix or report it before the truck rolls; anything that puts the truck out of service stays parked.
- If the last report listed defects, the repair is certified and you sign it
- Any defect you found today is repaired or written up before you leave
- At the end of the day, write a vehicle inspection report if you found a defect or one was reported to you
49 CFR 396.11 (driver vehicle inspection reports) and 396.13
Why this shows up in your insurance price
Brakes, tires and lights are where roadside inspectors find most equipment violations, and those violations feed the Vehicle Maintenance score in the federal safety measurement system. Underwriters read that score and your inspection history before they quote a renewal. A carrier whose trucks pass clean inspections is the one that keeps access to the better markets.
A thorough pre-trip is the cheapest safety program a fleet can run. It costs half an hour a day and it is the habit that keeps a small defect from becoming an out-of-service order, a crash or a claim.
See how your safety scores affect your rate →Frequently asked questions
How long should a pre-trip inspection take?
A thorough tractor-trailer pre-trip usually takes 20 to 50 minutes depending on the equipment and the load. A rushed five-minute walk-around is how brake, tire and light defects reach a roadside inspector.
Is a pre-trip inspection required by law?
Yes. Under 49 CFR 396.13 a driver must be satisfied the vehicle is in safe operating condition before driving it and must review the last vehicle inspection report. Under 49 CFR 392.7 the brakes, steering, lights and reflectors, tires, horn, wipers, mirrors, coupling devices, wheels and rims, and emergency equipment must be in good working order before the vehicle is driven.
What is the minimum tread depth on a truck tire?
Under 49 CFR 393.75, steer tires need at least 4/32 of an inch of tread at any point on a major groove, and every other tire needs at least 2/32 of an inch.
Do I have to fill out a report if I find nothing wrong?
For trucks carrying property, the end-of-day driver vehicle inspection report under 49 CFR 396.11 is required when the driver finds or is told about a defect or deficiency. Many fleets still require a report every day as company policy.
How does a pre-trip inspection affect my truck insurance?
Brake, tire and light violations found at roadside inspections feed the Vehicle Maintenance score in the federal safety measurement system. Underwriters read those scores and inspection histories when they price a carrier, so a habit of thorough pre-trips shows up as fewer violations and a cleaner file at renewal.
Clean inspections deserve a better quote
Send us your safety record with your quote request and we put it in front of the underwriter, so you are priced as the carrier you are today.