What 393.75A2 means in plain language
FMCSR 393.75A2 targets a specific and dangerous tire condition: the physical separation of tread material or sidewall material from the rest of the tire body. This isn't about tread depth being too low — that's a different violation. This is about tread or sidewall that is actively peeling away, chunking off, or delaminating from the casing beneath it.
When a tire's tread or sidewall separates, the structural integrity of the tire is compromised in a way that can lead to rapid deflation or a blowout at highway speed. Inspectors are trained to spot bulges, exposed cords, missing tread blocks, and any area where the rubber has pulled away from the belt or casing underneath.
The bottom line: if your tire looks like it's coming apart — even partially — you are exposed to this citation. A tire that appears to have intact tread depth can still fail this inspection point if separation is visible anywhere on the tire's surface or sidewall.
What our enforcement data actually shows
Across our inspection records, 393.75A2 has accumulated 11,338 all-time citations, making it the 210th most-cited code out of 3,036 FMCSR codes in our database. That puts it firmly in the top 7% of all codes by enforcement volume — this is not an obscure or rarely-enforced regulation.
In the last 12 months alone, our database shows 7,439 citations issued under this code, and 1,658 of those came in just the last 90 days. The monthly trend data tells a clear story: citations climbed from 580 in May 2025 to a recent peak of 784 in October 2025, and have remained elevated, hitting 762 in March 2026. Enforcement activity on this code is not slowing down.
Out of 11,338 all-time citations, 1,529 resulted in an out-of-service order — a 13.5% OOS rate. To put that in context, the all-FMCSR average OOS rate across all codes in our database is 31.4%. So 393.75A2 comes in well below that average, which means most drivers cited for this violation are allowed to continue operating. That said, 13.5% is not zero — roughly 1 in 7 citations still results in a driver being placed out of service on the spot. Whether you get cited and sent on your way or cited and parked depends heavily on where you are and who is doing the inspection.
Who gets cited most
Looking at the last 180 days of our inspection records, Texas dominates the citation count for 393.75A2 by an enormous margin — 3,485 citations with a 10.2% OOS rate. New Mexico comes in second with 38 citations but a dramatically higher OOS rate of 71.1%. Illinois ranks third with 28 citations and a 60.7% OOS rate.
That gap between Texas (10.2%) and New Mexico (71.1%) is not a rounding difference — it is a 60.9 percentage-point spread. If you're crossing into New Mexico or Illinois with a tire that's even borderline on separation, the odds of being placed out of service are substantially higher than they would be for the same tire condition inspected in Texas. Same violation, very different enforcement outcomes depending on the state.
The carrier-level data in our database is also worth noting. Our data shows fleets such as SERVICIO DE TRANSPORTE INTERNACIONAL Y LOCAL SA DE CV (USDOT 557341) with 167 all-time citations and TRANSPORTES AGUILA DE CIUDAD JUAREZ SA DE CV (USDOT 555365) with 137 all-time citations appearing at the top of the list. The concentration of Mexican-domiciled carriers in the top citation counts aligns directly with the co-occurring code 391.11B2-Z appearing 227 times in shared inspections over the last 90 days — a pattern that points to heavy enforcement activity at and near the southern border.
How severe is this compared to similar codes
Within the Vehicle Maintenance category, 393.75A2 sits in a different tier than the highest-volume codes. Consider 393.9(a) — Inoperable Required Lamps — which has 660,737 citations in our database with a 15.4% OOS rate. That code sees roughly 58 times the citation volume of 393.75A2. Or look at 396.3(a)(1) — Inspection/Repair/Maintenance General — with 236,919 citations and a 45.3% OOS rate, more than triple the OOS rate of 393.75A2.
Another useful comparison is 393.78 — Windshield Condition Defective — which has 157,894 citations but only a 0.3% OOS rate, meaning it's cited constantly but almost never results in a driver being parked. At 13.5%, 393.75A2 carries meaningfully more OOS risk than windshield violations, even though it is cited far less frequently overall. For a code ranked 210th out of 3,036, a 13.5% OOS rate is a genuine operational risk that warrants attention during every pre-trip.
How to avoid it
The co-occurring violation data from our last 90 days is one of the most practical prevention tools available. When 393.75A2 is cited, 276 of those same inspections also included a citation for 393.75C (Tire Tread Depth Insufficient on Other Axles). That means inspectors who find tread separation are also checking every axle for tread depth. If your tires are borderline on depth, they're also more likely to show separation — address both issues together.
- Walk every tire during your pre-trip, not just a glance. Run your hand along sidewalls to feel for bubbles, soft spots, or lifting rubber. Look at the tread surface for any chunks that have separated or are pulling away from the belt layer. FRHT tractors account for 4,075 of the all-time citations under this code — the highest of any vehicle make — so if you're running a Freightliner, make tire inspection a non-negotiable step.
- Check steer axle tires last and most carefully. Steer tires are under the most lateral load and most likely to develop sidewall separation that gets missed in a quick walk-around.
- Don't ignore co-occurring brake and lamp violations as signals. Our data shows 393.9 (Inoperable Required Lamp) appearing in 467 shared inspections and 393.47E (Slack Adjuster Defective) in 236 shared inspections alongside 393.75A2. An inspector who notices a bad lamp or a dragging brake is going to pull a full Level 1. If your tires have any separation, it will be found.
- Before crossing into New Mexico or Illinois, do a focused tire check. Our data shows OOS rates of 71.1% and 60.7% in those states respectively — inspectors there are pulling drivers for tire separation at a rate six times higher than in Texas.
- Flag any tire with visible belt edge separation for immediate replacement, not for monitoring. A tire that shows any separation at the belt edge or sidewall ply is not a watch-and-see situation. It is a pre-trip failure.