What 393.75F-SPEED means in plain language
Your commercial motor vehicle's tires come with a speed-restriction label. That label specifies the maximum safe speed at which that tire is rated to operate. FMCSR 393.75F-SPEED prohibits you from operating your CMV at speeds exceeding what that label allows.
This is straightforward: if your tire is labeled for a maximum of 65 mph, you cannot legally operate that vehicle at 66 mph or higher. The restriction exists because tires have engineering limits. Exceeding those limits risks heat buildup, blowouts, and loss of vehicle control—especially under load and over long distances.
While speed governors and company policy often keep drivers well below highway speed limits, this rule enforces a hard floor based on the tire manufacturer's engineering specification, not state law or fleet discretion.
What our enforcement data actually shows
Across our database of 13 million+ roadside inspection records, 393.75F-SPEED is exceptionally rare. We have recorded only 1 citation for this violation in our all-time history, with that single citation occurring in the last 12 months (September 2025). No citations have been issued in the last 90 days.
Out-of-service enforcement is zero: the 1 cited vehicle was not placed out of service. This means the inspector documented the violation but did not deem the vehicle unsafe enough to remove from the road immediately. The all-FMCSR average out-of-service rate is 31.4%, so 393.75F-SPEED sits dramatically below that threshold at 0.0%.
Nationally, this code ranks #2796 out of 3,036 FMCSR codes by citation volume. Its rarity underscores that most fleet tire programs and driver training successfully keep vehicles compliant.
Who gets cited most
Our inspection records show only one carrier with a citation for 393.75F-SPEED: Skaggs Trucking LLC (USDOT 1013225), with 1 citation recorded. The vehicle involved was a Kenworth (KW) unit. With only a single data point in our database, geographic or carrier-specific patterns cannot be reliably identified.
How severe is this compared to similar codes
393.75F-SPEED sits in the Vehicle Maintenance category alongside several far more frequently cited violations. For context:
- 393.9(a) (Inoperable required lamps) generates 660,737 citations with a 15.4% out-of-service rate—more than 660,000 times the citation volume of 393.75F-SPEED.
- 396.3(a)(1) (Inspection/repair/maintenance general) accounts for 236,919 citations with a 45.3% out-of-service rate, suggesting inspectors view maintenance deficiencies as serious enough to remove vehicles frequently.
- 393.78 (Windshield condition defective) has 157,894 citations but only a 0.3% out-of-service rate, indicating most windshield violations are minor and correctable on-site.
The gap between 393.75F-SPEED (1 citation) and even the least-cited peer codes (157,894 citations for 393.78) shows this is an enforcement outlier.
How to avoid it
Preventing a 393.75F-SPEED citation is simple and falls entirely within driver control:
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Know your tire labels before you roll. During your pre-trip inspection, locate and read the speed-restriction label on at least one tire per axle. If you don't know where the label is, ask your fleet maintenance team. It is usually on the tire sidewall or printed in your vehicle documentation.
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Never exceed the tire's rated speed, even if state law allows higher speeds. If your tires are rated for 65 mph but the highway limit is 75 mph, you must stay at or below 65 mph. This is a federal compliance issue, not optional.
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Verify tire replacements match your vehicle's speed rating. When your fleet replaces tires, confirm that the new tires meet or exceed the original speed rating. If downgraded tires are installed, you have a legal obligation to operate at the lower speed.
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Report mismatched or damaged tire labels to your dispatcher or safety manager. If a tire's label is unreadable, faded, or missing, or if you suspect a tire was installed with a lower rating than the vehicle requires, do not operate the vehicle. Report it for maintenance verification.
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Maintain steady, predictable speeds on long hauls. Fatigue and inattention sometimes lead to unintended speed creep. Use cruise control set to your tire speed limit, and treat that setting as your ceiling—not your baseline.
The extreme rarity of this citation (1 in 13 million inspections) reflects that most drivers and fleets maintain this compliance without incident. Staying within your tire's rated speed is both a safety requirement and a straightforward legal obligation.