Tire tread is the key factor that indicates when you need to replace your vehicle's tires. Tread provides you with the necessary traction to safely stop and turn. Lastly, treads on your tires help funnel water out from under the tire to minimize hydroplaning on wet roads.  The U.S. Department of Transportation suggests that motorists replace tires when they've worn down to 2/32 inch (or 1.6 mm).  Signs of Wear Besides tread depth of less than 2/32 inch, other signs can indicate the need for new tires, including: Exposed fabric or cord on the tires Bump, bulge, or knot that impacts the tire structure Unrepairable punctures Uneven wear caused by driving on a flat tire Bent, cracked, rusty, or damaged rim/wheel Improper tire repairs and services While tread depth is an obvious indicator, it can be difficult to measure an increment that tiny. Most professionals use a tread depth gauge to measure tread. But if you don't have one on hand, you can use a penny ... read more