Prevention FAQ — FMCSR 393.65C: Tires Flat or Leaking

Inspectors are looking for two distinct conditions: a tire that is completely flat (loss of air pressure) and a tire with an audible air leak (hissing sound when the vehicle is stationary or moving slowly). Our inspection records show 48 citations in Texas over the last 180 days, with a 64.6% out-of-service placement rate, indicating inspectors in high-enforcement zones are quick to place vehicles OOS for this violation. The 74.7% OOS rate across all 245 all-time citations suggests this is treated as a critical defect—far above the 31.4% all-FMCSR average. Inspectors typically use a visual inspection combined with a listening test around all tires during the walk-around. Pay particular attention to sidewall condition and valve stem integrity, as these are common entry points for slow leaks.

Your pre-trip must include: (1) Visual walk-around — check all tires for obvious flat spots, bulges, or visible punctures; (2) Sidewall and tread inspection — look for cuts, cracks, or uneven wear that may indicate slow leaks; (3) Valve stem check — ensure no corrosion or leakage around the stem; (4) Inflation verification — press firmly on tire sidewalls to feel for firmness (do not rely on appearance alone); (5) Listening test — with the engine off, move around the vehicle and listen for any audible hissing. Document findings on the vehicle inspection report (VIR). If the driver detects any flat or leaking tire, the vehicle must not be operated. A defective tire paired with maintenance issues (396.3A1 co-occurs in 9 recent inspections) often points to skipped pre-trips or inadequate pressure monitoring systems.

Drivers must complete a Vehicle Inspection Report (VIR) before each trip and note any tire defects observed. Carriers must retain: (1) Daily VIRs — signed by driver, retained for 12 months minimum; (2) Tire maintenance logs — including inflation checks, rotation dates, repair records, and replacement dates for each tire position; (3) Tire pressure monitoring records — if your fleet uses automated systems, archive daily readings; (4) Repair receipts — from tire shops documenting what was replaced or patched, with dates and mileage; (5) Mechanic inspection reports — from pre-trip inspections identifying any tire issues before they become citations. When a 393.65C citation occurs, attach the VIR from that date to the citation record. This documentation defends against inaccurate citations and demonstrates a systemic prevention program to safety auditors.

Across 13 million inspections, we see 393.65C frequently paired with three systemic issues: (1) 396.3A1 (general inspection/repair failure) — 9 shared inspections in the last 90 days — indicates drivers or maintenance staff are missing tire defects during routine checks. Root cause: inadequate pre-trip training or skipped inspections. Solution: implement mandatory pre-trip audit checklists with supervisor spot-checks. (2) 393.9 (inoperable lamp) — 8 co-occurrences — suggests vehicle was not properly inspected before dispatch. Root cause: rushed turnaround times. Solution: enforce minimum inspection time gates before departure. (3) 383.23A2 (no CDL) — 5 co-occurrences — may indicate drivers are untrained in basic vehicle checks. Root cause: hiring gaps or onboarding shortcuts. Solution: require all drivers to pass a hands-on vehicle inspection assessment during hiring.

After a tire is repaired or replaced, follow this verification protocol: (1) Shop documentation — obtain a detailed repair receipt showing the tire location (position), repair type (patch, plug, or replacement), tire size, and DOT/sidewall markings; (2) Pressure confirmation — verify the tire is inflated to the manufacturer's specification for the vehicle's GVWR (check the door jamb or fuel door placard); (3) Visual re-inspection — walk around the vehicle and ensure the repaired tire matches the condition of others; no bubbles, uneven wear, or leakage sounds; (4) Post-repair VIR — have the driver or shop technician sign a new VIR specifically documenting the repair and confirming readiness for service; (5) Proof-of-inspection sticker — if your fleet uses them, ensure a dated sticker is visible on the driver's side door. Do not return a vehicle to service on a tire that has been plugged more than once or shows tread wear below 2/32 inch.

Within 48 hours of a citation, conduct a structured root-cause review: (1) Review the VIR from the citation date — did the driver conduct a pre-trip? Were tire conditions noted? If the VIR is blank or missing, this indicates non-compliance with VIR procedures; (2) Interview the driver — ask whether they felt any handling changes, heard any noise, or noticed pressure loss before inspection; (3) Inspect the vehicle — if the citation vehicle is still in your fleet, perform a full tire and suspension inspection to identify any ongoing defects; (4) Check maintenance history — review tire pressure logs and rotation records for the 30 days prior to citation; gaps suggest mechanical oversight; (5) Driver retraining — have the driver perform a supervised pre-trip with a safety manager, focusing on tire inspection steps; (6) Escalation decision — if this is a repeat citation (check your fleet's CSA safety audit history), consider reassigning the driver or additional training. Document all findings and corrective actions in the driver's file.

Although 393.65C is not an out-of-service-eligible code in the regulatory framework, across our 13 million inspection records it carries a CSA severity weight of 8 and is ranked #1165 of 3,036 FMCSR codes. Its 74.7% out-of-service rate — more than double the 31.4% all-FMCSR average — means inspectors treat this as a critical safety defect, and FMCSA will count it heavily in Vehicle Maintenance BASIC scoring. A single citation can increase your Safety Event score; multiple citations within 36 months can push your BASIC to Alert status (Above Average), triggering scrutiny in the next audit. If your fleet operates in Texas (48 citations in 180 days) or New Mexico (100% OOS rate across 3 recent citations), the regional enforcement intensity is high. Implement proactive tire pressure monitoring systems and monthly self-audits to prevent accumulation.

Our vehicle make data shows Freightliner (FRHT) dominates with 64 citations, followed by Ford (36) and Kenworth (25), suggesting a fleet composition issue or make-specific tire vulnerabilities. Tailor training to your fleet's primary makes: (1) Pressure monitoring basics — teach drivers how to read tire pressure labels, understand load-based inflation, and use a manual pressure gauge as backup if TPMS fails; (2) Sidewall damage recognition — show photos of common defects: radial cracks, bulges, cuts, and valve stem corrosion specific to each vehicle make's tire mounting; (3) The listen-and-feel test — walk drivers through the audible leak test (quiet engine, moving slowly around tires listening for hiss) and the palm-press firmness check; (4) When to report vs. when to ground — clarify that any flat or audibly leaking tire = DO NOT OPERATE; no exceptions; (5) Seasonal adjustments — pressure changes 1 psi per 10°F; cold weather increases flat-tire risk. Conduct training quarterly with recorded competency checks.

Over the last 90 days, our records show 26 citations; over the last 12 months, 150 citations. This pattern suggests enforcement is consistent but lumpy — October 2025 saw 27 citations (the peak month), while April 2026 shows only 1. We recommend: (1) Weekly pre-trip compliance audit — have a safety manager spot-check 10% of pre-trip VIRs to ensure tire sections are completed and signed; (2) Monthly physical vehicle audit — inspect at least 5 vehicles from your fleet with a hands-on tire walk-around, pressure gauge, and listening test; document findings; (3) Quarterly trend review — pull your citation history, tire repair logs, and failed VIRs; identify patterns (e.g., specific drivers, routes, seasons, or vehicle makes); (4) Annual tire pressure system calibration — verify TPMS sensors and manual gauges are accurate. This cadence aligns with the 90-day enforcement spike and gives you enough data points to detect root causes before citations accumulate.

DataQs challenges should be filed when: (1) The citation is factually incorrect — e.g., the inspector recorded a tire as flat when your repair receipt and post-citation VIR prove it was inflated to spec and the driver heard no leak; (2) The VIR contradicts the citation — if your driver's signed VIR from that date shows a pre-trip was conducted and no tire defects noted, and the citation was issued hours later due to road damage (not a pre-existing defect), the burden of proof shifts; (3) The inspection was incomplete — if the citation does not reference which specific tire position was cited or the inspector did not document pressure or audible leak evidence, request clarification through DataQs; (4) Timeline disputes — if your tire repair receipt is dated the same day or day prior to the citation with photo evidence, DataQs can overturn the violation. However, do not file if the citation is accurate; this damages your credibility. Focus challenges on documentation gaps and factual inaccuracies. Work with your safety manager and legal counsel to assemble evidence before submission.