The Law

According to most states’ laws, tires are legally worn out when they have worn down to 2/32″ of remaining tread depth. To help warn drivers that their tires have reached that point, tires sold in North America are required to have indicators molded into their tread design called “wear bars” which run across their tread pattern from their outside shoulder to inside shoulder. Wear bars are designed to visually connect the elements of the tire’s tread pattern and warn drivers when their tires no longer meet minimum tread depth requirements.

How you can check:

U.S. coins can be substituted for a tire tread depth gauge as tires wear to the critical final few 32nds of an inch of their remaining tread depth.

  1. Place a penny into several tread grooves across the tire. If part of Lincoln’s head is always covered by the tread, you have more than 2/32″ of tread depth remaining.
  2. Place a quarter into several tread grooves across the tire. If part of Washington’s head is always covered by the tread, you have more than 4/32″ of tread depth remaining.
  3. Place a penny into several tread grooves across the tire. If the top of the Lincoln Memorial is always covered by the tread, you have more than 6/32″ of tread depth remaining.