Every year, FMCSA and CVSA release the same headline finding with mathematical consistency: brakes, tires, and lighting defects together generate over 75% of all commercial vehicle out-of-service orders in North America. The three categories don't tie — there's a clear, durable ranking. Brake system defects lead by a wide margin (24.4% of vehicle OOS in 2025, plus an additional 16.7% for "20% defective brakes" — 41.1% combined). Tires sit second at 21.4%. Lighting violations come third at 14%. For fleet and safety managers, the operational question isn't whether to address all three — it's where to invest first, because the prevention strategies differ sharply: brakes require under-vehicle inspection that walk-arounds miss, tires need pressure-gauge discipline at pre-trip, and lights are the most preventable failure category on the entire OOS list. This data-driven comparison breaks down each category by 2025–2026 violation frequency, repair cost, downtime impact, and prevention strategy — with the 2026 Roadcheck escalation that pushed the overall OOS rate to nearly 33%. For fleet managers building a defect-prevention program that targets the three categories that drive 75% of risk, Start your free HVI trial to put guided pre-trip workflows and defect routing on every driver, or book a demo to see how HVI surfaces brake, tire, and lighting issues before they become OOS orders.
The data verdict — brakes lead, and the gap is widening
This isn't a close race. Across every recent Roadcheck cycle — 2023, 2024, 2025 — brake system defects have generated more OOS orders than tires and lights combined. The pattern holds regardless of which category CVSA names as the year's "vehicle focus" — brakes don't need extra attention to keep leading the table.
Brake defects — the #1 category, by a wide margin
What gets you OOS: Slack adjusters out of spec, audible air leaks at chambers, brake lining below 1/4", cracked or scored drums, defective ABS, brake pushrod travel exceeding limits. The 20% defective brakes rule places a vehicle OOS when at least one-fifth of the braking system has a defect — even if each individual defect is minor.
- Slack adjuster adjustment out of limits
- Audible air leaks at chambers/lines
- Brake lining below minimum thickness
- Inoperative brakes on any wheel
- Brake pushrod travel exceeding spec
- Defective ABS warning system
- Most catchable issues require under-vehicle access
- Level II walk-arounds miss most brake defects
- Slack adjusters drift continuously with use
- Heat cycling stresses drums and pads
- Air system leaks build slowly between PMs
- No driver feedback until issue is severe
Tire defects — the #2 category, and the most-cited single violation
What gets you OOS: Steer tires below 4/32" tread depth, drive tires below 2/32", sidewall damage exposing cord ply, inflation below 50% of max PSI, flat tires, improperly repaired tires, tires not rated for the load or highway use. The single FMCSA violation "Tires – All others, leaking or inflation less than 50%" was the 4th most-cited violation nationwide in 2025.
- Steer tire tread below 4/32" (auto-OOS)
- Drive tire tread below 2/32" (auto-OOS)
- Inflation below 50% of max PSI
- Sidewall cuts exposing cord/ply
- Visible bulges or improper repairs
- Load-rating mismatch with cargo weight
- Tread depth and sidewall damage are visible
- Drivers can catch most issues at pre-trip
- Pressure gauges make verification simple
- Multiple driver/dispatch opportunities to catch
- Slow leaks usually show on walk-around
- Tire failures rarely surprise an alert driver
Lighting defects — the #3 category and the most preventable failure on the list
What gets you OOS: Inoperative required lamps — particularly brake lights, turn signals, tail lights, clearance lights, marker lights, headlights. The fix is almost always a $5 bulb. The catch rate at roadside is high because lights are visible from outside the cab — and the prevention rate is high because drivers can spot every required lamp in a 60-second walk-around.
- Inoperative brake lights
- Inoperative turn signal lamps
- Missing or non-functional clearance lights
- Burned-out marker lights
- Inoperative or improperly aimed headlights
- Trailer tail/identification light failures
- Cheapest repair on the OOS list ($5 bulbs)
- No diagnostic equipment needed to detect
- Visible from outside the vehicle, instantly
- Driver pre-trip catches 95%+ if done
- Fastest fix in the yard (under 5 minutes)
- Highest ROI on inspection discipline
Three-way comparison matrix — at a glance
Side-by-side-by-side: how each category compares on the dimensions that matter for fleet planning. The pattern is sharp — brakes are expensive and hard to catch, lights are cheap and easy to catch, tires sit between them on both axes.
The 2026 escalation — OOS rate nearly doubled in May
The 2025 CVSA Roadcheck recorded an 18.1% vehicle OOS rate. The 2026 event, run May 12–14, saw a dramatic escalation: the final-week OOS rate settled at approximately 32.8% — nearly double the prior year. Day 2 alone added 4,826 inspections, 8,373 violations, and 1,559 OOS orders. The escalation matters for fleet managers because it suggests enforcement is tightening, not loosening — and brake/tire/lighting defects are still driving the volume.
Penalty exposure — what each OOS event actually costs
Beyond the immediate repair, an OOS order triggers a cascade: roadside downtime, lost load revenue, potential CSA score damage, and direct civil penalties under the FMCSA 2026 schedule. Penalties compound per occurrence — a fleet with a pattern is looking at far more than a single fine.
The prevention strategy — different category, different mechanism
Because the three categories have such different access requirements and driver-detection rates, the prevention strategy for each is fundamentally different. Treating them as a single "do better pre-trips" project misses what actually works for each.
Brake defects largely escape walk-around inspections. The defense is rigorous scheduled PM: quarterly slack-adjuster checks, annual 49 CFR 396 Appendix A inspection, air leak-down tests at PMs. Pre-trip air leak audible check catches some issues but not all.
Tire defects are catchable, but only if drivers actually measure rather than eyeball. Tread gauge on every tire, every shift. Pressure gauge on any soft-looking tire. Required-field digital inspections force actual measurement instead of "OK" responses.
The most preventable category in the OOS data. Lights on, hazards on, full perimeter walk. The cost of prevention is 60 seconds of attention. Lights only get cited when drivers don't actually walk the truck — software that requires a photo of every flagged light forces the walk-around.
How HVI eliminates the categories driving 75% of OOS orders
Brakes, tires, and lights each fail for a different reason — but a single inspection platform can address all three by enforcing the specific discipline each category requires. HVI's eDVIR workflow maps directly to the three prevention mechanisms above.
Brake PMs fire automatically on actual machine hours — quarterly slack-adjuster checks, annual 49 CFR 396 Appendix A inspection, leak-down tests. Never missed because of memory.
Drivers can't submit a DVIR with "OK" on tires — actual tread depth and PSI readings are required, photo-verified. The category that should be catchable becomes the category that always is.
Every lighting category requires a photo on the inspection — confirming the driver actually walked the perimeter with lights energized. Lights are the cheapest fix and the easiest to prevent — HVI eliminates the rest of the gap.
Any "Fail" on brakes, tires, or lights auto-creates a work order with photo and vehicle ID. The truck cannot dispatch with the defect open — eliminating the "dispatched with known OOS defect" violation ($19,277 max).
HVI's inspection templates pre-map to the 2026 CSA "Driver Observed" BASIC — capturing exactly the evidence that protects driver and carrier scores from defects in these three categories.
Every inspection, work order, repair certification indexed by VIN and date. When the auditor arrives, brake, tire, and lighting compliance is documented and exportable in under a minute.
Fleets that systematically eliminate brake, tire, and lighting defects from pre-trip cut their OOS exposure by 75% with no new equipment and no extra labor. Start your free HVI trial to put guided inspections on every driver, or schedule a 30-minute walkthrough to see how HVI maps to your current PM program.
Frequently asked questions
Three categories. 75% of OOS exposure. One inspection platform that addresses all three with the discipline each requires.
HVI enforces PM scheduling for brake systems, required-field measurements for tires, and photo-verified walk-arounds for lighting — eliminating the three categories that drive the majority of fleet OOS orders in 2026.
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