How to Check Tire Tread Depth: The Penny Test

Tire Tread-Depth is the thickness of the rubber remaining on your tire tread. Tire tread is measured in 32nds of an inch and most tires start out with 10/32nds or 5/16th of an inch of rubber to grip the road.

As you drive, the rubber wears down and becomes less effective at controlling your vehicle. Once your tire tread is below 1/8th of an inch of rubber, most industry experts suggest preparing to replace.

If you are down to 1/16th of an inch, your tires are considered worn out, and most states require immediate replacement. Driving in inclement weather like this could put you in a bad situation without much warning.

Tire Tread Depth Chart

Tire tread depth is crucial for your vehicle’s safety, it impacts many things like traction, handling, and overall performance. Below is a general tire tread depth chart, which can help you understand when it’s time to replace your tires:

Tire tread depth chart

The tire tread depth gauge measures in 32nds of an inch. Good tire tread depth will be 6/32 or deeper. If the depth is 4/32, you should start thinking of replacing your tires and getting new ones. 2/32 or less means that you should change your tires ASAP. The amount of tire tread can affect your stopping distance, making a drive in wet or snowy conditions more dangerous.

Tread Depth (in 32nds of an inch)Tread Depth (in mm)ConditionAction Needed
10/32″ and above7.94 mm and aboveNew tire conditionNo action needed
8/32″ – 9/32″6.35 – 7.14 mmExcellent tread conditionNo action needed
6/32″ – 7/32″4.76 – 5.56 mmGood tread conditionMonitor tread wear
4/32″ – 5/32″3.17 – 3.97 mmFair tread conditionConsider replacing soon
2/32″ – 3/32″1.58 – 2.38 mmPoor tread conditionReplace tires immediately
0/32″ – 1/32″0 – 0.79 mmBald tires (illegal in many places)Replace tires immediately

When to Replace Tires:

In the United States, tread depth is measured in 32nds of an inch and in most states, it’s illegal to drive on tires with less than 2/32 of one inch of tread.

  • Tires should be replaced when the tread depth reaches 2/32″ or less
  • Tires may need to be replaced sooner depending on driving conditions
  • Have tires inspected by a professional if tread depth is low

How to Check Tire Tread Depth?

When it comes to checking tire tread, there are a number of methods that can help you know if it’s time to replace a tire. The heavily worn tread will prevent a tire from performing as designed and can lead to unsafe driving conditions. One of the simplest, most common ways to check tread depth requires nothing more than a penny and a few moments of your time.

How to Check Tire Tread Depth with a Penny?

Checking tire tread with a penny is an easy way to measure tread depth:

The Penny Test

The idea of the penny test is to check whether you’ve hit the 2/32” threshold. Here’s how it works:

Place a penny between the tread ribs on your tire. A “rib” refers to the raised portion of tread that spans the circumference of your tire. Tire tread is composed of several ribs.

Turn the penny so that Lincoln’s head points down into the tread.

See if the top of his head disappears between the ribs. If it does, your tread is still above 2/32” , If you can see his entire head, it may be time to replace the tire because your tread is no longer deep enough.

When performing the penny tire test, remember not only to check each tire, but to check various places around each tire. Pay special attention to areas that look the most worn. Even if parts of your tread are deeper than 2/32”, you should still replace the tire when any areas fail the penny test.

Consistent wear around the whole tire is normal, but uneven tread wear could be a sign of improper inflation, wheel misalignment, or a variety of other things. If you see uneven tread wear, you should have a technician inspect your vehicle.

Other ways to check the Tire thread

Quarter Tire Tread Test

Similar to the penny tire test, the quarter test can show you how much tread you have remaining on your tires. Specifically, the quarter test will show you if your tread depth has worn to or below 4/32nds of an inch.

To perform the quarter test, take a quarter and place it into your tread groove with George Washington’s head facing downward. If you can see the top of Washington’s head, then your tires have worn below 4/32nds of an inch.

Below 4/32”, your tires will experience a serious loss in stopping power and hydroplaning resistance. We highly recommend replacing tires worn to or below 4/32nds of tread depth.

How to Check Tire Tread Depth with a Tire Tread Depth Gauge?

While the “penny test” can work, the car industry recognized the need for a tool to accurately measure tire tread. A tire tread depth gauge is inexpensive, usually less than $10, and it takes all the guesswork out of checking tire depth, giving you an exact reading, so you’ll know when it’s time to get a new set of tires.

How to Check Tire Tread Depth
Tire Tread Depth check using a gauge.

Whenever you check the tire tread, you should also:

  • Check the tire pressure.
  • Inspect for any visible damage to the tread or sidewalls.
  • Check for any tire rot or disintegration.
  • Check to see if the wear is uneven.

If you notice any issues with your tires, schedule a service appointment at any of the Basil Family Dealerships’ service centers to have it taken care of as soon as possible.

Tread Wear Indicator Bars

Another way to check tread depth is to look at the treadwear indicator bar that’s molded into most tires. The bars are located at the bottom of the tread grooves in several locations around the tire.

When these bars become visibly flush with the adjacent ribs the tire has no more than 2/32″ of tread remaining. This is a visible indication for when you should replace your tires.

Why Check Tire Tread Depth?

With adequate tire tread depth, your car is able to grip the road. This is especially important when roads are snowy or wet, or when you’re driving on less-than-ideal surfaces. Once tread becomes shallow, your tires are more prone to slipping and sliding, creating a dangerous situation for yourself and other drivers on the road.

When your tires are worn, other components of your vehicle can begin to wear prematurely, too, as your vehicle experiences excess strain. While new tires can be a big investment, they’re an investment worth making.

Why Worry About Tread Wear?

The most important reason to worry about tread wear is safety.

When your tire treads are worn, your car may respond poorly to adverse weather conditions like rain and snow. With good treads, your car will grip the road better. Also, having insufficient tread is considered illegal in many states. And finally, worn treads can make other parts of your car wear prematurely.

Potential Problem Areas:

  • Excessive wear in the center tread indicates over-inflation of the tire.
  • Excessive wear on shoulders may signal problems such as under-inflation of the tire.
  • Uneven tread wear indicates poor wheel alignment.
  • Excessive wear on one side of the tire signals an incorrect camber angle.
  • If the treads on the outer section become knobby, it may signal problems with the toe-in value