FMCSR 393.75C: Tire Tread Depth (Non-Steer Axles) — Driver FAQ

Almost certainly not — but it has happened. Across all-time inspection records, 393.75C carries a 4.3% out-of-service rate (1,664 OOS placements out of 38,759 citations). That is dramatically lower than the all-FMCSR average OOS rate of 31.4%, and the violation is officially flagged as not OOS eligible under the standard criteria. The small slice of OOS placements likely reflects cases where inspectors found additional qualifying defects on the same axle. In short: the citation alone won't park your truck, but if inspectors find accompanying issues, the calculus changes fast.

A 393.75C citation carries a severity weight of 5 in the FMCSA CSA scoring system. That base score is then multiplied by a time-weight factor — violations within the last 6 months count at 3×, violations 6–12 months old count at 2×, and anything older counts at 1×. So a fresh citation effectively hits your Vehicle Maintenance BASIC with a weighted score of 15 points. That score accumulates with any other Vehicle Maintenance violations on your record and is visible to shippers, brokers, and enforcement for up to 24 months.

Take these steps immediately:

1. Measure every non-steer tire — the threshold is less than 2/32 inch tread depth on any tire on a non-steer axle. Replace any tire at or below that line before your next dispatch.
2. Check your lights — our inspection records show 393.9 (Inoperable Required Lamp) appeared in 1,668 of the same inspections as 393.75C in just the last 90 days. A bad tire and a dead lamp together dramatically raise your inspection score.
3. Inspect brakes and fuel lines — 393.45B2UV (brake tubing/hoses) and 396.5B (fuel system leak) co-occurred in 730 and 615 of those same inspections, respectively.
4. Pull your periodic inspection paperwork — 396.17C (no proof of periodic inspection) showed up in 534 shared inspections.
5. Document all repairs with signed shop receipts and keep them in the cab.

It is serious in volume, less so in severity. At #83 out of 3,036 FMCSR codes by citation count, 393.75C is cited far more often than most rules — 38,759 times all-time. But its 4.3% OOS rate is modest compared to peer Vehicle Maintenance codes: for example, 396.3(a)(1) (general inspection/maintenance) carries a 45.3% OOS rate across 236,919 citations, and even 393.9(a) (inoperable required lamps) runs at 15.4%. The practical risk of 393.75C is its high co-occurrence with other violations that do trigger OOS — so the citation is a signal that a deeper inspection problem may exist.

Yes, you can submit a challenge through FMCSA's DataQs system (the Request for Data Review, or RDR process). Because 393.75C is an equipment-based finding — a specific, measurable condition (tread depth below 2/32 inch) — the strongest grounds for a challenge are: (1) the officer used a faulty or uncalibrated tread-depth gauge, (2) the cited tire was incorrectly identified as a non-steer axle tire, or (3) the inspection report contains factual errors such as the wrong vehicle or axle position. Documentation-based challenges — for example, showing a repair invoice timestamped before the inspection — can also support removal. Keep dated shop records and any photos taken at the scene.

Texas is by far the most active enforcement state. In just the last 180 days, our inspection records show 10,476 citations in TX alone, with a 4.5% OOS rate (476 trucks placed out of service). Iowa ranked second with 319 citations (0.0% OOS rate), and North Carolina third with 283 citations and a notably higher 6.0% OOS rate. New Mexico (211 citations) and Illinois (170 citations, 15.3% OOS rate) round out the top five. If your lanes run through Texas or cross into North Carolina and Illinois, tread checks before dispatch are especially important.

Don't wait. Enforcement volume is high and rising: our inspection records logged 5,491 citations in just the last 90 days, and the monthly trend shows consistent enforcement above 1,900 citations per month from May 2025 through March 2026, peaking at 2,391 in October 2025 and 2,373 in March 2026. While the 4.3% all-time OOS rate means most cited drivers kept rolling, Illinois inspectors placed 15.3% of cited vehicles out of service in the last 180 days — meaning equipment-based discretion varies by jurisdiction. A tire that scrapes by one inspector may not pass the next. Replace it before the next dispatch.

Both — but in different ways. Under FMCSA's CSA system, a citation recorded during a roadside inspection attaches to the carrier's Vehicle Maintenance BASIC score, since the carrier is responsible for ensuring the vehicle is roadworthy. However, if the driver is identified as the responsible party on the inspection report, the violation can also appear on the driver's record and affect their driver-specific CSA data. This means a carrier accumulating 393.75C citations — like the top-cited carriers in our records, some with 100+ all-time citations — sees BASIC score degradation regardless of driver turnover.