FMCSA Out-of-Service Checks: What Inspectors Cite on Tractors and Trailers Put Out of Service
FMCSA out-of-service checks by equipment type: four checks (tires, brakes, air hoses, air leaks) covered 67.8% of tractors put out of service, and five covered 75.5% of trailers.
- Published
- Cites
- 49 CFR 396.9
Four checks (tires, brakes, air hoses and air leaks) covered 67.8% of the tractors put out of service at roadside in the last 12 months, and five checks (tires, lamps, brakes, breakaway and emergency brakes, and cargo securement) covered 75.5% of the trailers. "Covered" means the unit had at least one out-of-service violation in one of those checks. This page lists the checks, in order, for tractors and for trailers.
How these numbers were made
- Dataset: FMCSA vehicle inspection data, public roadside inspections, one current version per inspection.
- Window: inspections from 2025-10-19 to 2026-10-18.
- Unit: one inspected tractor or trailer in one inspection. A truck inspected twice counts twice.
- Population: units with at least one violation carrying the out-of-service flag. Tractors: n = 168,252. Trailers: n = 190,523.
- What the number is: a mix among units put out of service. It is not a rate, because units inspected with no violations are not in this data. It says what the units put out of service had, not how likely any truck is to be put out of service.
- Checks: each check is a family of FMCSA violation codes that this page groups by code prefix, so a check covers every defect under its rule. Tires, for example, is every out-of-service tire violation: flat or leaking, damaged, worn or overloaded. A unit can have violations in several checks, so the shares add to more than 100%. Units whose only out-of-service violations fall in no listed check count in n but in no check, so coverage does not reach 100%.
Which checks show up most on tractors put out of service?
Tractors put out of service, n = 168,252. The cumulative column is the share of tractors that had an out-of-service violation in that check or any check above it.
| Rank | Check | Tractors with an out-of-service violation in it | Share of tractors put out of service | Cumulative share |
|---|---|---|---|---|
| 1 | Tires: flat, leaking, damaged, worn or overloaded | 71,035 | 42.2% | 42.2% |
| 2 | Brakes: 20% or more defective | 21,802 | 13.0% | 53.7% |
| 3 | Air hoses and tubes damaged | 18,091 | 10.8% | 62.9% |
| 4 | Air leaks and air-loss-rate failures | 10,984 | 6.5% | 67.8% |
| 5 | Cargo securement | 4,995 | 3.0% | 70.2% |
| 6 | Hub and wheel-seal leaks | 4,684 | 2.8% | 72.1% |
| 7 | Lamps and reflectors | 4,313 | 2.6% | 74.2% |
| 8 | Fuel leaks | 3,268 | 1.9% | 75.5% |
| 9 | Breakaway, emergency and tractor-protection brakes | 3,163 | 1.9% | 76.9% |
Tires were found on 42.2% of the tractors put out of service. The four checks at the top covered 67.8%. For how the air system fits together, see the air brake system.
Which checks show up most on trailers put out of service?
Trailers put out of service, n = 190,523.
| Rank | Check | Trailers with an out-of-service violation in it | Share of trailers put out of service | Cumulative share |
|---|---|---|---|---|
| 1 | Tires: flat, leaking, damaged, worn or overloaded | 60,439 | 31.7% | 31.7% |
| 2 | Lamps and reflectors | 48,038 | 25.2% | 54.9% |
| 3 | Brakes: 20% or more defective | 18,898 | 9.9% | 63.0% |
| 4 | Breakaway, emergency and tractor-protection brakes | 17,530 | 9.2% | 69.6% |
| 5 | Cargo securement | 14,642 | 7.7% | 75.5% |
| 6 | Air hoses and tubes damaged | 6,235 | 3.3% | 78.0% |
| 7 | Air leaks and air-loss-rate failures | 3,219 | 1.7% | 79.1% |
| 8 | Hub and wheel-seal leaks | 3,140 | 1.6% | 80.2% |
| 9 | Fuel leaks | 245 | 0.1% | 80.3% |
Among trailers put out of service, 31.7% had a tire violation and 25.2% had a lamp violation. The five checks at the top covered 75.5%. For the lighting side, see semi trailer lighting and wiring.
How do tractors and trailers differ?
The order differs by equipment type, so "the top checks" is a different list for each. Tires are first on both. On tractors the next three are brakes, air hoses and air leaks; on trailers the next are lamps, brakes, and breakaway and emergency brakes. That check means different parts on each: on trailers it is mostly the breakaway system, and on tractors, at rank 9, it is mostly the tractor-protection and trailer-supply valves.
What an out-of-service order is
An out-of-service order is a roadside determination by authorized FMCSA personnel under 49 CFR 396.9(c). The page Unsafe operation, failed inspections and out-of-service orders explains what it requires and how it differs from a failed annual inspection. The common DOT inspection questions page answers the related questions.
What these numbers do not say
They describe what inspectors recorded on the units they put out of service. They are not a safety rating or a finding about any carrier, truck or trailer, and they say nothing about whether any vehicle is compliant. Inspectors choose which trucks to stop, so the units here are not a sample of all trucks on the road.
This page reports aggregates of public FMCSA vehicle inspection data for the window stated above and cites 49 CFR 396.9. It is informational only and does not constitute legal or regulatory advice. Consult the current eCFR for the complete text.