Tire Inspection: A Complete Fleet Tire Inspection Guide

Tire failures cause blowouts, road debris, and crashes, and tire defects are a frequent out-of-service category at roadside inspections. But the financial case is just as strong. Underinflation is the number-one killer of tire life and fuel economy: a chronically soft tire runs hot, wears its shoulders, burns extra fuel, and risks a casing-destroying blowout that ends any chance of retreading. Inspection is how you catch all of that before it costs you the casing.

Inspect tires when they are cool for an accurate pressure reading, and work the same sequence on every vehicle so nothing gets skipped. Park on level ground and chock the wheels if you will be crouching at the tires. Wear gloves; debris embedded in tread can cut.

Use a calibrated gauge on cold tires and compare to the target pressure for that tire and load, not the maximum stamped on the sidewall. On dual setups, check both tires in the pair, because one soft tire silently overloads its mate. A thump-test with a mallet is a rough field screen for flats on duals but is not a substitute for a gauge. Record actual pressures so trends show which positions lose air.

Measure tread depth in the major grooves with a tread-depth gauge, checking multiple points across the tire and around its circumference. Differences across the tread face reveal alignment and inflation problems. FMCSA sets legal minimums by axle position, and most fleets pull tires before the legal limit to preserve casing value for retreading. The full procedure and pull-point strategy are covered in the tire tread depth guide.

Look for cuts, bulges, cracking, exposed cords or fabric, and impact damage on both sidewalls, including the inner sidewall on duals. A bulge means a damaged casing and the tire must come off, full stop. Check the shoulders for irregular wear, and look between duals for trapped stones or debris. Any sidewall damage that exposes cord, any bulge, or any cut deep enough to reach the body plies is a remove-from-service condition.

A missing valve cap lets dirt and moisture into the valve core and is a common slow-leak cause. Confirm every valve stem is capped, undamaged, and not cracked or leaking, and that extensions on inner duals are secure. It is the smallest item on the inspection and one of the most common reasons a tire mysteriously loses pressure between checks.

These are legal minimums, not fleet targets. Running a steer tire down to exactly 4/32 leaves no safety margin and no retread casing value, which is why most fleets set internal pull points above the legal floor. More on that in the tread depth deep dive.

The penny test puts Lincoln's head into a tread groove: if the top of his head stays visible, tread is at or below 2/32 and the tire is at the legal floor for non-steer axles. The quarter test uses Washington's head to flag roughly 4/32, the steer-axle limit. These coin tests are handy for a driver's quick screen, but they are pass/fail estimates.

A tread-depth gauge gives an actual number you can log and trend, which is what a fleet needs to manage retread timing and spot uneven wear early. Use coins for a fast field check and a gauge for anything you record. The measurement detail lives in the tire tread depth article.

Because most irregular wear traces back to inflation or alignment, a fleet that fixes those two things upstream sees the biggest gains in cost per mile.

The key is that the driver walkaround feeds the same system as the PM. When a driver notes a soft tire on the DVIR, it should open a work order rather than evaporate in a verbal handoff. That continuity is what turns daily checks into trend data you can act on.

TPMS is a powerful complement to manual inspection, not a replacement. Sensors can fail, drift, or miss sidewall and tread damage entirely. The strongest programs pair continuous pressure monitoring with a disciplined physical walkaround that a sensor cannot do.

Tire spend scales fast. A light-truck tire might run $150 to $300, while a commercial truck tire can run $300 to $600 or more, multiplied by tires per vehicle and vehicles in the fleet. The levers that inspection controls are direct: correct inflation can meaningfully extend tread life and improve fuel economy, and protecting the casing makes a tire a retread candidate, often at a fraction of new-tire cost, instead of scrap.

An in-house program needs three things: a standard procedure every technician and driver follows, the right tools (calibrated gauges, tread-depth gauges, an air supply), and a system to log readings against each tire position so trends are visible. Assign target pressures by axle and load, define internal tread pull points above the legal minimum, and review wear-pattern data to catch alignment and suspension problems fleet-wide.

Mounting, balancing, and retread coordination may stay in-house or go to a tire vendor depending on volume and equipment, but the inspection and the data should stay with the fleet. Owning the data is what lets you negotiate with tire suppliers, time retreads, and prove the program's ROI.

Standardize with a checklist so every inspection is consistent and every reading is recorded. Attach it to the pre-trip and to the PM work order template.