What 393.65(b) means in plain language
FMCSR 393.65(b) prohibits operating a commercial motor vehicle when any tire is flat or has an audible air leak. This is straightforward: if you can hear air escaping from a tire or the tire has completely lost pressure, you cannot legally operate that vehicle on a public road.
The regulation applies to all tires on your truck—drive tires, trailer tires, steer tires, and dual wheels. A tire doesn't have to be visibly torn or damaged. The key word is audible: an inspector can cite you if they can hear the leak, even if the tire still has some pressure. A flat tire is any tire that has lost enough air that it no longer supports the vehicle's weight properly.
This is a maintenance standard, not a safety afterthought. Flat or leaking tires reduce braking efficiency, increase rollover risk, and can fail suddenly at highway speeds. Inspectors flag this violation because it poses real hazard on the road.
What our enforcement data actually shows
Across our 13 million+ inspection records, this violation is extremely rare. We have recorded only 30 all-time citations for 393.65(b)—ranking it #1799 out of 3,036 FMCSR codes by citation volume. In the last 12 months, we saw zero citations. In the last 90 days, we saw zero citations.
When this violation is cited, it almost never results in an out-of-service order. Of the 30 citations on record, only 1 vehicle was placed out of service—a 3.3% OOS rate. By comparison, the all-FMCSR average OOS rate is 31.4%. This low out-of-service rate suggests that most drivers cited for 393.65(b) correct the tire issue quickly or that inspectors find the violation during minor infractions rather than severe roadworthiness failures.
The scarcity of citations indicates that most commercial drivers are performing pre-trip inspections and addressing tire problems before they escalate to audible leaks or full flats.
Who gets cited most
Our data shows no state breakdown is available in the enforcement records for this code, so we cannot rank states by citation frequency. However, our inspection records do capture which carriers have received citations. Among carriers with multiple citations, Adrian Ives Portales Aguilar (USDOT 2456389), Benjamin Herrera Cano (USDOT 554927), Chaqui SPR de RL (USDOT 2594210), and Cristian Melendez Cisneros (USDOT 3342159) each have 2 citations. The remaining citations are distributed across individual owner-operators and smaller fleets with 1 citation each.
The diversity of carriers cited suggests this violation cuts across fleet size and operational model—no carrier type is immune, but the low overall volume means even repeat offenders are rare.
How severe is this compared to similar codes
393.65(b) sits within the Vehicle Maintenance category alongside codes that inspectors encounter far more frequently. For context:
- 393.9(a) — Inoperable required lamps has been cited 660,737 times with a 15.4% OOS rate. Lighting violations are routine; tire deflation is exceptional.
- 396.3(a)(1) — Inspection/repair/maintenance general has 236,919 citations and a 45.3% OOS rate. That code covers broader maintenance failures and results in out-of-service orders nearly half the time.
- 393.11 — Lighting devices/reflectors has 179,734 citations with a 1.8% OOS rate, also more common but still lower severity than many inspection-failure codes.
The gap in citation volume is stark. 393.65(b) is cited roughly 22,000 times less frequently than inoperable lamps and 8,000 times less frequently than general maintenance failures. This rarity reflects how effectively most fleets manage tire condition.
How to avoid it
Before every trip:
- Walk around your truck and trailer. Look at every tire—drive, trailer, steer, and duals. Kneel down and visually inspect for cuts, bulges, or obviously low profile. If a tire looks flat or you see uneven wear, mark it for repair before departure.
- Listen for leaks. On quiet mornings or in a silent facility, walk slowly around the vehicle and listen. A tire with an audible leak will hiss. If you hear one, do not operate the vehicle. Report it and get it repaired.
- Check tire pressure when cold. Use an accurate gauge and compare to the placard on your driver's door or frame. Low pressure often precedes audible leaks. Correct any underinflation before rolling.
- Inspect during your trip. During breaks, especially on hot days, visually scan all tires again. Heat can accelerate a slow leak.
- Know your vehicle. Our data shows Freightliner vehicles (4 citations), International trucks (3 citations), and KW models (2 citations) appear most frequently in 393.65(b) enforcement records. If you operate these makes, add tire checks to your pre-trip routine and be alert to any pressure-loss pattern on that model.
- Report and repair immediately. If you discover a flat or leaking tire during your trip, pull over safely, and notify dispatch. Do not continue operating the vehicle. Repairs are cheap; the citation and downtime are costly.
Most drivers never receive this citation because they perform basic tire inspections. The fact that you were cited means a tire condition was missed or developed unexpectedly. Use this as a reminder to slow down before departure and trust your eyes and ears.