Brake Violations Are a Top OOS Cause

• Brake violations account for nearly 24% of all out-of-service violations during International Roadcheck and six of FMCSA’s top 20 recorded vehicle violations in 2025, the largest single category by a wide margin.
• Brakes dominate the data because they’re a high-wear component that’s also fast for inspectors to check at roadside, combining high failure rate with high detectability.
• Because recent violations carry three times the CSA weight of older ones, a cluster of brake citations from a short enforcement window can move a fleet’s Vehicle Maintenance BASIC, and insurance renewal exposure, faster than the same citation count spread across a year.

Ask any roadside inspector what pulls the most trucks out of service, and the answer is consistent year over year: brakes. During CVSA’s International Roadcheck, brake violations accounted for nearly 24% of all out-of-service violations recorded, the single largest category, ahead of tires, lights, and cargo securement combined in most years. During Brake Safety Week 2025 specifically, more than 15,000 vehicles were inspected and 15.1% were placed out of service for brake-related defects. Six of the top 20 vehicle violations FMCSA recorded across 2025 involved defective, worn, or out-of-adjustment brakes.

Why the Numbers Look Like This

Brakes are a wear component under constant mechanical stress, which makes them statistically likely to develop issues between scheduled maintenance intervals in a way that, say, a headlight assembly usually doesn’t. They’re also one of the fastest systems for a trained inspector to evaluate at roadside, pushrod travel measurements, audible leak checks, and visual drum/rotor inspection can all be done quickly without pulling the vehicle into a full-service bay. That combination of high failure rate and fast detectability is exactly why brakes dominate the out-of-service statistics year after year, independent of any single enforcement campaign.

The Data, Component by Component

• Air leaks and system pressure issues are among the fastest violations an inspector identifies, often audible before the vehicle is fully stopped.
• Slack adjuster and pushrod travel violations indicate the brake isn’t applying full force even when the component itself looks intact, this is a frequent source of “we didn’t know it was a problem” citations, because the defect isn’t visually obvious to a driver.
• Drum and rotor condition, this year’s specific Brake Safety Week focus area, covers thickness below manufacturer minimums, cracking, and heat damage from dragging brakes.
• ABS malfunction indicators are treated as an independent violation regardless of base brake condition, since ABS is a required safety system on its own.

What the Data Means for CSA Scoring

Every one of these violations, wherever and whenever it’s recorded, feeds the CSA Vehicle Maintenance BASIC. Given how dominant brakes are in the overall out-of-service data, it follows that Vehicle Maintenance is one of the BASICs where fleets most commonly see their percentile climb, not because of a single bad audit, but because brake-related citations accumulate steadily across routine inspections throughout the year, not just during named campaign weeks.

Recent violations carry more weight than older ones in the CSA calculation, violations from the most recent one to six months are weighted at three times the value of older data, which means a cluster of brake citations picked up in a short window, like an enforcement blitz, can move a fleet’s percentile faster than the same number of citations spread across a full year.

What the Data Means for Insurance

Underwriters treat CSA data, and specifically the Vehicle Maintenance BASIC, as a direct risk signal. Carriers with scores above the intervention threshold in safety-related BASICs commonly see premium surcharges in the 15% to 40% range at renewal. Given that brakes are consistently the single largest contributor to out-of-service violations nationally, a fleet’s brake maintenance discipline is arguably one of the highest-leverage variables it controls when it comes to managing renewal costs — more controllable, in most cases, than crash history or driver turnover.

Turning the Data Into a Maintenance Strategy

The out-of-service numbers point to a clear prioritization for fleets with limited maintenance budget or shop time:

1. Treat brake system checks as the highest-frequency item in your PM schedule, not an annual or semi-annual item.
2. Build ABS lamp verification into every documented pre-trip, since it’s a fast check with outsized violation risk if skipped.
3. Track which units generate repeat brake citations and flag them for component replacement rather than repeated spot repairs.
4. Review your CSA Vehicle Maintenance BASIC trend quarterly, not just after an audit letter arrives.

How Simplex Group Uses This Data With Fleets

Simplex Group reviews CSA trend data alongside insurance renewal timing for the fleets we work with, so brake-related patterns get flagged as an underwriting conversation before renewal, not discovered during it.

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