Measuring Tire Depth with a Depth Gauge

• 1). Position the tire tread depth gauge between the tread on one of your tires. A tire tread depth gauge is a small, hand-held device with a plunger that is attached to a white measuring stick. The white measuring stick displays numbers indicating depth. A stopper prevents the plunger from showing incorrect information.
  
  
• 2). Push the plunger of the tire tread depth gauge all the way down. The stopper on the tire depth gauge will stop the plunger at the tread's depth and the white measuring stick will display the depth.
  
  
• 3). Check the measurement by reading the number at the bottom of the measuring stick, which is located where the metal of the tire depth gauge meets the white measuring stick. Higher numbers indicate more depth. Most gauges read in 32nds of an inch and in millimeters, differentiated by red or black numbers.
  
  

Measuring Tire Depth with a Coin

• 1). Press a penny or a quarter between the treads of your tire.
  
  
• 2). Note where the tread of your tire meets the coin. If the tread covers Lincoln's head (on a penny), then you have have more than 2/32-inches of tread remaining. If the tread covers part of Washington's head (on a quarter), you have more than 4/32-inches remaining.
  
  
• 3). Flip the penny over and use the Lincoln Memorial side to check for deeper depth. If the top of the Lincoln Memorial is covered, you have more than 6/32-inches of tread remaining.
  
  
• 4). Repeat these steps at various intervals on each of your tires. If your tires have less than 2/32-inches of tread, they are too worn and must be replaced.