Tires are the single most inspected component category during Level I roadside inspections, and for good reason. According to FMCSA safety data, tire-related violations consistently rank among the top contributors to commercial vehicle out-of-service orders nationwide. Officers don’t write OOS orders based on gut instinct — they work from a precise, standardized measurement framework published by the CVSA. If your pre-trip is missing tire checks, you are leaving your operating authority exposed to the exact thresholds detailed below.

What Triggers a Tire OOS Order: The Regulatory Foundation

Federal regulations under 49 CFR §393.75 establish the baseline tire standards for commercial motor vehicles. The CVSA North American Standard OOS Criteria translate those federal standards into the field-level measurement benchmarks inspectors carry during every inspection. Understanding the distinction matters: the CFR sets the rule, but the CVSA OOS criteria define precisely when a violation becomes severe enough to park a vehicle.

Tire violations fall under CVSA Item 3 in the OOS criteria matrix. Any single qualifying defect on any tire — steer, drive, or trailer — can result in an immediate OOS order. There is no grace threshold for “borderline” conditions once a specific measurement is crossed.

CFR §393.75: The Source Document

The five violation categories under §393.75 that generate the most OOS activity are:

• §393.75(a) — Tires with a flat condition, or audible air leak
• §393.75(b) — Inadequate tread depth on steer axle tires (less than 4/32 inch)
• §393.75(c) — Inadequate tread depth on all other tires (less than 2/32 inch)
• §393.75(f) — Tires with visible tread separation, exposed cords, or sidewall damage
• §393.75(h) — Tires with a cut or other condition that exposes the ply or cord

Each of these maps directly to a specific CVSA measurement criterion. Officers are trained to apply the tread depth gauge, visual inspection protocol, and inflation check in sequence.

Tire Out of Service Criteria CVSA: The Exact Measurements

This is where enforcement becomes binary. Once an inspector’s gauge reads below the published threshold, or a visual condition is confirmed, the OOS order is not discretionary — it is mandatory.

Steer Axle Tread Depth

The CVSA OOS threshold for steer axle tires is less than 4/32 inch of tread depth measured in any two adjacent major tread grooves at three separate locations around the circumference. Officers use a calibrated tread depth probe — not a visual estimate. A reading of 3/32 inch at any qualifying location on a steer tire is a hard OOS.

This is the most consequential measurement in tire enforcement. Steer tires control vehicle direction under braking and emergency maneuvers. FMCSA data indicates steer tire violations generate a disproportionate share of tire-related crash involvement compared to their inspection frequency.

Drive and Trailer Axle Tread Depth

For all non-steer positions, the CVSA threshold drops to less than 2/32 inch, again measured in any two adjacent major tread grooves at three locations around the tire circumference. While this appears more lenient, worn drive tires remain a significant OOS generator in annual inspection cycles, particularly on older trailer fleets where tire rotation schedules are inconsistent.

For a comprehensive breakdown of how these defects are classified and documented, the analysis at tire defects out of service criteria covers the inspection documentation process in detail.

Flat, Leaking, or Mismatched Tires

Beyond tread depth, the following conditions result in an immediate OOS regardless of tread measurement:

• Any tire that is flat or has an audible leak — zero tolerance, no measurement required
• Sidewall exposed ply or cord — any visible cord exposure at any location
• Tread separation — any portion of tread separating from the carcass
• Cut or crack exposing ply or cord — applies to tread, sidewall, or bead area
• Dual tire contact — dual tires touching each other or any component of the vehicle

Dual tire contact is frequently overlooked during pre-trips. It is listed explicitly in the CVSA criteria because contact generates heat concentration sufficient to cause rapid tread separation at highway speeds.

How Officers Conduct the Field Inspection

Inspectors approach tire inspection in a systematic sequence that mirrors the pre-trip inspection items most drivers skip. The sequence typically runs: visual inflation check, sidewall condition scan, tread depth probe on steer axles, probe on drives and trailers, dual spacing verification, and valve stem/cap condition check.

The Tread Depth Probe Protocol

Officers are not required to probe every tire on a multi-axle vehicle before writing an OOS. Under CVSA field protocol, a confirmed violation on one tire triggers the OOS for the vehicle. However, thorough inspectors will probe all axle positions to document the full scope of violations for citation purposes, which directly impacts the carrier’s SMS percentile.

Inflation and Visual Conditions

Inflation defects require no measurement instrument — a flat or audibly leaking tire is a direct OOS condition. Sidewall damage is assessed visually, and officers are trained to distinguish between superficial surface checking (not OOS) and actual cord exposure (OOS). The distinction is physical penetration to the reinforcement layer, not the depth of any surface marking.

Enforcement Trends and Carrier SMS Impact

FMCSA SMS data consistently shows tire violations clustering in the Vehicle Maintenance BASIC. Carriers operating with SMS percentiles above 75 in Vehicle Maintenance face elevated roadside inspection selection rates, creating a compounding enforcement cycle. A single tire OOS on a Level I inspection generates a recordable violation that remains in SMS calculations for 24 months.

It is worth noting that tire violations do not exist in isolation during roadside inspections. Officers who identify tire defects typically conduct a full Level I, where brake deficiencies are a parallel enforcement priority — see the breakdown of brake violations that trigger immediate OOS orders for the measurement thresholds that run parallel to tire enforcement. Similarly, if cargo securement irregularities are visible, the inspection scope expands further — the cargo securement failures generating the most citations follow a comparable measurement-based enforcement logic.

Staying Current with CVSA Threshold Updates

The CVSA revises its OOS criteria on a published cycle. Thresholds that applied during the previous inspection year are not guaranteed to carry forward unchanged. For carriers building compliance programs around specific measurements, tracking the CVSA 2026 OOS criteria changes is an operational requirement, not optional reading.

The measurement thresholds described in this post reflect the current published CVSA OOS criteria framework. Any threshold verification for active compliance programs should be cross-referenced directly against the CVSA OOS criteria source document before implementation.

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Data sourced from CVSA OOS Criteria and FMCSA public records. Verify current enforcement thresholds at fmcsa.dot.gov.