Tread Depth and How You Check It

A key factor in determining the health of your tires is tread depth. Tread depth is the vertical measurement between the top of the tread rubber to the bottom of the tire’s deepest grooves. It is measured in 32nds of an inch.

For example, new tires are usually 10/32” or 11/32” tread depths. Some truck, SUV, and winter tires may have deeper tread depths. Tread depth is vital in determining how well your tires will handle and funnel water away from the tire. This ensures it can maintain good contact with the road during inclement weather. Keep in mind the only thing between you and the road is your tires.

The National Highway Traffic Safety Administration (NHTSA) recommends replacing tires when they reach 4/32” of remaining tread depth, and many states legally require tires to be replaced at 2/32” depth.

Why should you replace your tires before they reach 2/32”? It is at that measurement when your tread is worn out at dangerous levels. This increases the probability of hydroplaning on water or losing traction in snow. Both of which are potentially dangerous situations.

At 4/32” you have some grip remaining, but your traction degrades fast. For safety purposes, you need to get new tires.

So how do you check your tread depth? Accurately measuring tread depth can be a challenge. For complete accuracy, we recommend stopping in a local Tire Discounters where our trained professionals can run a free air pressure check and a free tread depth check.

If by chance you have a tire tread depth gauge, you can check it at home. Don’t have a tread depth gauge? You can either do a quick penny test or look at the tread wear indicator bars on the tire itself.

The Penny Test for Tread Depth

The penny test uses a U.S. Lincoln penny. Simply place the penny into a tread groove. Make sure that Lincoln’s head points down into the groove. If you can see his entire head, this means your tread is around the 2/32” threshold. It is time to replace the tire. If Lincoln’s head disappears or is always covered by the tread, the tire meets the 2/32” standard.

When doing the penny test, check various places around the tire to ensure you have an accurate measurement. Make sure you look closely at those parts of your tread that look worn the most.

What if my tires’ tread depth fails the penny test?

If your tire fails the penny test in any spot of the tire tread, you should immediately replace the tire.  Consistent wear around the tire is normal. Uneven tread wear is possibly a sign of improper inflation, incorrect alignment, or a shock, strut or suspension issue.

If you have a tread depth gauge, all you do is place the probe into a groove in the tread and press the shoulders of the probe flat and read the result. Tread depth gauges are inexpensive and any brand should work fine if it measures in 32nds of an inch and millimeters.

A built-in measurement of tread depth are the wear indicator bars located in grooves on the tire. If you look closely in the tread grooves there will be indentations periodically spaced around the entire tire and those indentations are set at 2/32”. If you look at your tread and it is flush with one or more of those tread bars, it’s time to replace the tire. Make sure you check each tread groove and review the entire tire to ensure your tires are in good condition.

Your neighborhood Tire Discounters can fully inspect and diagnose any problems you might have with uneven tread wear and give you peace of mind on the safety of your tires.