What is the Penny Test?

Inspecting Tire Tread Depth Using a Penny

The penny test is a simple trick to help you determine if your tires should be replaced.   Simply turn a penny upside down and insert it between your tire treads.  If all of Lincoln’s head is exposed, it’s time to replace your tires.  This trick works because there is 1/16 of an inch between the top of Lincoln’s head and the edge of the penny which is the minimum legal limit for tread depth.


When to Replace Tires

Inspecting Tire Tread Depth Using a QuarterThe penny test is a little outdated and to be safe you really should replace your tires when your tread depth gets below 2/16’s of an inch.  Fortunately, 2/16’s of an inch is the exact distance on a quarter from the top of Washington’s head to the edge of the quarter. So your best bet is to use a quarter to measure tread depth.

Tire wear bars for tread depthOther Ways to Measure Tire Tread Depth

New tires sold in the U.S. and Canada are required to have indicators molded into their tread design going across the tire tread called wear bars.  When tires are worn to the point that the wear bars are the same height as the tread, they no longer meet the minimum tread depth requirements and the tire must be replaced.

Why is the Penny Test important?

When tire treads are worn down it’s dangerous and can be illegal.  With little or no tread depth, tires can lose performance and traction in rain or snowy conditions.  Water escapes through the treads to allow your rubber to meet the road.  When the water cannot escape, the tire floats on top of the water causing hydroplaning and the driver loses control.

If you find you need new tires, make sure you also know how to find the best price on car tires