What 393.75A4 means in plain language
This citation means an inspector found a cut in one of your tires deep enough to expose the inner ply material or belt structure underneath the rubber surface. A tire's strength depends on those internal layers staying intact and protected. When a cut breaches that outer rubber layer, the tire loses structural integrity and becomes unsafe to operate, even if it still holds air.
The regulation requires all tires on a commercial motor vehicle to be free from cuts that expose these internal components. This is a straightforward mechanical standard: if the damage goes through the outer rubber to the layers beneath, the tire fails inspection. It doesn't matter whether the cut happened on a drive axle, trailer axle, or steer axle—the requirement is the same across all tire positions.
What our enforcement data actually shows
Across our 13 million+ inspection records, 393.75A4 has generated 2,139 all-time citations and ranks #519 out of 3,036 FMCSR codes by citation volume. In the last 12 months, we recorded 1,337 citations, with 293 in the last 90 days.
When cited for this violation, your truck is placed out of service in 18.3% of cases. That's notably lower than the all-FMCSR average out-of-service rate of 31.4%, meaning inspectors often allow you to continue after citing the defect—though that depends on how many tires are affected and your compliance history. Still, the 391 out-of-service placements (all-time) show this is not a violation inspectors dismiss lightly when the damage is severe or widespread.
The monthly trend over the last 12 months shows enforcement has remained steady, hovering between 99 and 130 citations per month, with July, August, September, October, and November each exceeding 120 citations. This suggests tire condition inspections are a consistent enforcement priority year-round.
Who gets cited most
Our data shows Texas dominates the citation count, with 617 citations in the last 180 days and a 10.7% out-of-service rate. North Carolina ranks second with 12 citations but shows a much higher 83.3% out-of-service rate, indicating inspectors there take tire cuts more severely. New Mexico, with 6 citations, shows a 100% out-of-service rate, reflecting stricter enforcement on this specific defect in that jurisdiction.
Carriers in our top-cited list include operations such as Transporte Internacional Lopez Ochoa SA de C V (USDOT 1041907) with 21 all-time citations and RS Transfer SA de CV (USDOT 1156825) with 10 citations. Neither pattern indicates negligence; rather, these carriers operate high-volume fleets with more roadside exposure, making individual defects more likely to appear in enforcement data.
How severe is this compared to similar codes
In the vehicle maintenance category, 393.75A4 sits well below the severity threshold of codes like 396.3(a)(1) Inspection/repair/maintenance - general, which has 236,919 citations and a 45.3% out-of-service rate. It also compares favorably to 393.9(a) Inoperable required lamps, which shows 660,737 citations and a 15.4% out-of-service rate despite being roughly in the same enforcement zone.
By contrast, codes like 396.17C No proof of periodic inspection generate far more citations (212,081) with a 0.0% out-of-service rate, suggesting administrative violations are cited more often but treated less severely. The 393.75A4 data indicates this is a defect-based citation that sits in the mid-range of enforcement volume and relative severity.
How to avoid it
Perform a thorough pre-trip tire inspection every shift. Walk around your entire vehicle, including all trailer tires, and look for cuts, chunking, foreign objects, and bulges. Run your hand along the sidewall and tread. If you find a cut that you can see into (rather than just a surface nick), report it immediately and do not operate the vehicle until the tire is replaced or repaired.
Check tire tread depth regularly. Our data shows 393.75C (Tire tread depth insufficient on other axles) commonly co-occurs with 393.75A4 in 50 shared inspections over the last 90 days. Worn tires are more vulnerable to cuts because the rubber is thinner. Use a penny or tread-depth gauge at multiple points on each tire—if you're at or below 2/32 inch, replace the tire before road conditions force the issue.
Inspect brake components and suspension during your walk-around. Slack adjuster defects (code 393.47E, 39 co-occurring inspections) and steering system wear (code 393.53B, 31 co-occurrences) often appear alongside tire defects. A worn brake component can cause uneven tire wear or pulling, and poor steering alignment can lead to sidewall scrubbing and cuts. Catching these early keeps your whole drivetrain safe.
Address lighting and windshield condition. Inspectors who find 393.75A4 also cite inoperable lamps (393.9, 94 co-occurrences) and windshield defects (393.78, 59 co-occurrences) in the same roadside check. This pattern suggests comprehensive vehicle condition is scrutinized during a single inspection. Keep all lights functional and your windshield clear to avoid drawing extra attention that compounds your exposure.
Be alert to the most commonly cited vehicle makes. Freightliner trucks (FRHT) account for 676 of all citations for this code, followed by Kenworth (KW) with 336. If you operate one of these popular models, factor in that they may be inspected more frequently simply due to market prevalence. This doesn't mean they're less reliable, but higher citation counts reflect higher inspection volume.
Don't operate while fatigued. Code 392.2RG (Operating a CMV while ill or fatigued) appears in 54 shared inspections with 393.75A4. Tired drivers miss pre-trip details and are more likely to encounter road hazards that cause tire damage. A thorough, alert walk-around takes only a few minutes and catches damage before an inspector does.