Free CDL Pre-Trip Inspection Checklist

Approach and paperwork, engine compartment with the engine off, in-cab start-up and gauges, lights check on foot, then the walkaround in a fixed loop — left steer axle, front, side and frame, coupling system, drive and trailer axles, rear — and the air brake test last. This checklist is laid out in that order because the test is scored that way and because doing it the same way every time is what stops you skipping a step.

49 CFR 392.7 names eleven: service brakes including trailer brake connections, the parking (hand) brake, steering mechanism, lighting devices and reflectors, tires, horn, windshield wipers, rear-vision mirrors, coupling devices, wheels and rims, and emergency equipment. 49 CFR 396.11 requires a written report covering the same eleven at the end of the day's work. Everything else on this checklist exists because it is how you confirm one of those eleven is sound.

With the engine stopped and the brakes released, pressure may not drop more than 2 psi in a minute on a single vehicle or 3 psi on a combination. With the brakes fully applied, the limits are 3 psi and 4 psi respectively, plus an extra 1 psi per minute for each additional towed vehicle. Those figures are in 49 CFR 570.57(a)(5) and (a)(6).

On a vehicle built to FMVSS No. 121, the low-pressure indicator must activate at a level not less than 60 psi. On older vehicles the floor is 50 psi (49 CFR 570.57(a)(3)). The governor should cut in no lower than 80 psi and cut out no higher than 135 psi unless the manufacturer specifies otherwise, and the compressor should raise pressure from 85 to 100 psi in 45 seconds or less on any vehicle built after 1 March 1975.

No. The front wheels of a bus, truck, or truck-tractor need at least 4/32 inch of tread depth in a major groove; every other position needs at least 2/32 inch. Measure away from tie bars, humps, and fillets, which read deeper than the real groove. Both figures are in 49 CFR 393.75(b) and (c).

A charged, securely mounted fire extinguisher labeled with a UL rating of 5 B:C or more (10 B:C if the load requires placarding), at least one spare fuse of each type needed unless the unit uses circuit breakers, and either three bidirectional reflective triangles, six fusees, or three liquid-burning flares. Flame-producing devices are barred on explosives loads, flammable gas or liquid cargo tanks, and any vehicle running on compressed gas. See 49 CFR 393.95.

It covers the same components examiners expect a driver to identify and check, in the same sequence. Scoring and the exact call-outs vary by state, so learn the routine here and then practice the wording against your own state's CDL manual before the test.

A thorough pre-trip on a tractor-trailer runs 15 to 30 minutes when it is done properly, and the air brake test alone accounts for several of those because two of the steps are timed one-minute measurements. It gets faster with repetition. The brake test is the part that never gets shorter.

If it affects safe operation you do not drive — 49 CFR 392.7 makes that the driver's judgment call, not dispatch's. Record it on the DVIR at the end of the day's work, and 49 CFR 396.11(a)(3) requires the carrier to repair and certify anything likely to affect safe operation before the vehicle goes out again.

The low-air warning and the parking-brake tug test. Both only matter if something is already wrong, so they get rushed or skipped, and examiners watch for exactly that. The other common miss is measuring tread with a gauge instead of eyeballing it — a steer tire at 3/32 inch looks fine and is out of service.