Glossary

Tread depth

Last reviewed: 2026-05-20

The depth of usable tread measured in major grooves with a proper gauge. Federal minimums: 4/32 inch on steer axles, 2/32 inch on other positions (49 CFR 393.75).

Measure several spots because irregular wear can hide the lowest point. The legal minimum is a floor, not a target for removal — many fleets set higher thresholds to preserve casing value.

Real-World Use

A tire can look acceptable from the outside shoulder while the inside rib is already near the steer-axle removal depth of 4/32 inch.

Reference Sources

Sources used for context and verification of regulatory thresholds, inspection criteria, and compliance references on this page.

Gov 49 CFR 393.75 - Tires (Electronic Code of Federal Regulations, reviewed 2026-05-20)
Ind CVSA North American Standard Out-of-Service Criteria overview (Commercial Vehicle Safety Alliance, reviewed 2026-05-20)

What to Pair It With

Read this term with the full tire sidewall, vehicle rating information, manufacturer documentation, and the actual condition of the tire.

This site is for general information only. It does not replace professional tire service, DOT compliance advice, tire manufacturer instructions, vehicle manufacturer recommendations, or fleet policy.