Tread depth is the primary indicator of a tire's health. New tires typically start with of tread.
Tires degrade over time due to environmental exposure, regardless of how much tread is left. How to Buy Tires: A Step-by-Step Guide - US News Cars when to buy new tires
For a stricter safety margin, use a quarter. If Washington's head is fully visible, your tread is below 4/32", and you should plan for a replacement soon. Tread depth is the primary indicator of a tire's health
