Glossary

Tread groove

Last reviewed: 2026-05-20

The open channel between tread ribs or lug blocks that channels water from the contact patch and contributes to wet-weather traction. Federal tread depth measurements are taken in major tread grooves. As grooves wear shallower, wet-weather drainage and traction capability decrease.

Tread depth is measured in major grooves, not on rib faces. The groove depth determines removal timing, not rib surface appearance.

Real-World Use

A driver reporting poor wet-weather traction on steer tires — which still appear to have rubber on the rib surfaces — discovers through measurement that the grooves have worn to 4/32 inch, the steer removal threshold.

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.