Used Semi Truck: Pre-Purchase Inspection Checklist

Work through this before you buy a used Class 8 tractor. Ticks save on this device; print it to take to the yard.

Paperwork first

Get the current DOT periodic-inspection report and sticker (it is required to be on the vehicle)
Check the title for salvage, rebuilt, or glider status
Verify the ENGINE model year, not just the chassis / VIN year

Emissions (2010-and-newer era)

Confirm the DPF / EGR / SCR aftertreatment is intact and NOT deleted (a delete is a federal liability that follows the truck)
If you will register in California, confirm a 2010-or-newer compliant engine

DOT reject items (49 CFR Part 396, Appendix A)

Exhaust: no leaks forward of or directly below the cab
Brakes: linings within limits, no air leaks, slack adjusters right
Steering: play within spec, no binding
Tires: legal tread depth, no exposed cord or sidewall damage
Frame and crossmembers: no cracks or previous bad repairs

Drivetrain economics

Compare engine hours against odometer miles (idle hours age an engine the odometer does not show)
Price an in-frame overhaul into the offer if the engine is high-hour

A working checklist, not legal or professional advice. See the full guide for the reasoning behind each step, and the model records for prices and known failures.