Tread Depth Wear Calculator

When to Use This Tool

Use this calculator when a tire has an unexpected tread-depth reading at a maintenance stop and you need to estimate whether it will reach the next scheduled service interval or should be pulled early. It is also useful for establishing a baseline wear rate on a new tire line in a new application, so you can build a realistic rotation and replacement schedule.

How to Use

1. Measure the tread depth with a calibrated gauge at the shallowest point across the tread face. Measuring at the center rib alone will miss shoulder or rib-specific wear.
2. Enter the starting tread depth in 32nds of an inch. This is the depth when the tire was new or at the start of the mileage interval you are measuring.
3. Enter the current tread depth in 32nds. If the tire shows irregular wear, use the lowest reading from any position across the tread face.
4. Enter the miles driven between the two measurements. Use odometer records rather than estimated mileage.
5. Enter your removal depth target in 32nds. Federal minimum for steer tires is 4/32, other positions 2/32 — but most fleets pull earlier. Use your fleet's actual pull point.
6. Click Estimate to see wear rate per 10,000 miles and rough remaining miles to removal depth.

Reading the Result

Wear rate output is an average over the measured interval. If alignment was corrected, pressure was adjusted, or the load changed during that interval, the future rate will differ from the past rate. Treat the remaining-miles estimate as a rough planning number, not a guarantee.

If remaining miles comes out lower than your next scheduled service stop, the tire needs a removal decision now — not at the next service. Flag it for inspection and measure again at the next stop if it is still in service.

If the wear rate is unusually fast, check the measurement technique first. Measure at three points across the tread face: inner rib, center rib, outer rib. Use the lowest reading. A fast rate on one rib but not the others indicates uneven wear from a mechanical cause — alignment, pressure, or suspension — rather than overall wear rate.

Example Scenario

A steer tire is measured after a known mileage interval at a scheduled maintenance stop. The starting depth, current depth, and miles driven are entered to estimate whether the tire will reach the next service stop at the fleet's pull depth. The result is used to decide whether to flag the tire for early removal or continue to the next scheduled stop.

Formula and Limits

wear rate = (starting depth − current depth) ÷ miles driven; remaining miles = (current depth − removal depth) ÷ wear rate

• Wear is not perfectly linear — rate changes with load, alignment, pressure, route, and season.
• A single low reading caused by a stone chip or local damage can make wear look faster than it is. Measure multiple points.
• Removal depth must comply with 49 CFR 393.75 minimums, manufacturer guidance, and fleet policy — the calculator does not enforce any of these.
• The result is a planning estimate. Inspect the tire physically before deciding whether it can remain in service.

This tool is for planning and rough screening only. It does not replace tire manufacturer load/inflation tables, vehicle placards, professional tire inspection, or compliance guidance from the applicable regulation or carrier policy.