eCFR
49 CFR 396.17 — Periodic Inspection (Annual Vehicle Inspection)
The annual vehicle inspection for every truck, tractor and trailer, tank trailers included. It’s separate from the cargo tank tests.
FMCSA’s periodic inspection, the annual check every commercial motor vehicle needs. In a combination, each unit counts on its own: tractor, trailer and converter dolly. Box trucks that qualify as commercial motor vehicles get it too.
The inspection checks the parts that keep the vehicle safe on the road, like brakes, lights, steering, suspension, tires, wheels and frame. It does not test the tank.
The cargo tank tests are a separate requirement in 49 CFR 180.407. They apply to the specification tank itself, not to a tractor or a box truck. A tank trailer needs both, and it can be current on one and overdue on the other.
Read the current text on eCFR.