Tread helps tires move water away from the contact patch and maintain grip. Measuring tread regularly can help you plan replacement before traction declines.
How to check
Use a tire-depth gauge across several spots on each tire. Built-in tread-wear bars are another visual indicator. Follow your state requirements and the tire manufacturer’s recommendations.
Check more than depth
Look for uneven wear, cracks, bulges, punctures, and embedded objects. Replace or inspect damaged tires promptly, and do not drive on a visibly deflated tire.