Vehicle Inspection and Pre-Trip Procedures
Purpose and method
A pre-trip inspection is a defect-detection procedure, not a ritual. You are hunting for anything that would make the vehicle unsafe or place it out of service: leaks, cracked belts, worn tires, loose lug nuts, dead lights, air leaks, and brake adjusters that are out of adjustment. Walk the same route every time - driver's door, left side, engine compartment, front, right side, then lights and coupling - so a skipped step becomes obvious.
What examiners ask about
Know the hard limits. Steer tires need at least 4/32 inch of tread; every other tire needs 2/32 inch. Look for cuts, bulges, exposed cord, and mismatched duals. Compare brake pushrod travel to the chamber's adjustment limit, and check that slack adjusters do not move more than about one inch by hand. Inside the cab, test the low-air warning, the parking brake, and every light and gauge. Carry the required emergency equipment: a charged fire extinguisher, warning triangles, and spare fuses.
Traps
Questions love to blur the two tread limits, or to describe a driver who "kicks the tires" and calls that an inspection. Another favorite: confusing the pre-trip with the en-route inspection required after the first 50 miles and then every 150 miles or 3 hours.
Worked example
A driver measures 5/32 inch on the left steer tire, 3/32 on both drive tires, and 3/32 on the right steer tire. The drives pass (above 2/32). Both steer tires fail the 4/32 rule, so the vehicle stays out of service until they are replaced.