Ensuring you follow safe driving practices is vital to keep yourself, others and your vehicle safe. Keeping track of your tires' tread is an essential factor to staying safe while on the road. Worn tires are more susceptible to punctures, provide less traction and are prone to popping while you're driving.
You can keep yourself and others safe by frequently checking your tires for wear and replacing your tires when they become unsafe to drive with. We've created this comprehensive guide to explain how a tire's tread keeps you safe and how to check your tires for wear.
Why Do Tires Have Treads?
Tire tread exists to give your car stability and traction while driving, and the tread is particularly helpful while in poor weather conditions.
Four components create the tread patterns on tires:
- Ribs: Ribs are the raised areas on a tire, and they're formed from grooves that go around a tire's circumference.
- Grooves: Grooves are indented channels that exist along the circumference of a tire.
- Tread blocks: Tire ribs are composed of many tread blocks. The tread blocks make contact with the road and provide the car with increased traction and safety.
- Sipes: Sipes are small indents within the tread blocks that add additional stability and traction. They increase a tire's grip in wet road conditions and help prevent hydroplaning by diverting the water to the sides of the tire.
There are also four primary types of tire tread patterns — symmetrical, asymmetrical, directional and asymmetrical directional. All tire patterns include unique combinations of the four components above. Specific treads provide different benefits, and the one you should choose depends on the roads you drive on most often and the weather in your area:
- Symmetrical: Symmetrical tread means both sides of the tires share the same tread pattern. Tires with symmetrical treads are a good fit for a car you drive daily, but they offer less traction on wet roads than other treads. Symmetrical treads provide you with smooth driving, high levels of stability for turns and low rolling resistance. Low rolling resistance requires less force to rotate the tires, which results in increased fuel efficiency.
- Asymmetrical: Asymmetrical tread tires have two different tread designs — one pattern on the outer half of the tire and a separate one on the inner half. The different patterns offer unique benefits, and asymmetrical treaded tires offer top-notch handling, high curve stability and superior traction on wet roads. Asymmetrical tires are excellent at diverting water away from the tire and also provide strong traction on dry, muddy or snow-covered roads. They also offer strong road-holding at high speeds.
- Directional: Directional treaded tires have a V-shaped pattern along the circumference of the tire's center. The directional tread offers high resistance to hydroplaning because of its ability to displace water away from the part of the tire that contacts the road. You're most likely to find directional treads on all-season or winter tires because of their strong grip for all road conditions, including wet and snow-covered roads.
- Asymmetrical directional: Asymmetrical directional tread patterns combine the best features of both asymmetrical and directional treads to provide the most traction in bad road conditions. This type of tread is most often used for high-performance vehicles and can be harder to find and more expensive than other treads.
Be sure to use the same tread pattern on all your tires rather than mixing different ones. You'll see the best results by using tires of the same brand, size and tread pattern.
How Much Tread Is on a New Tire?
The average tread depth on a new tire will measure between 10/32 to 11/32 of an inch. You can find deeper treads if you're purchasing off-road tires, with some measuring upwards of 15/32 of an inch.
Why Does Tire Tread Wear Matter?
Ensuring your tire tread doesn't wear past a certain level is vital to stay safe on the road, reduce premature wear and tear on your vehicle and adhere to the law.
The National Highway Traffic Safety Administration (NHTSA) performed a study and found that 26.2% of tire-related crashes occurred on cars that had tires with an unsafe level of tread. When your tires wear out and the tread depth is reduced, you face a higher risk of a car accident due to several factors:
- Heat buildup: Tires heat up while driving because of the friction of rubber on pavement. Proper tread depth allows for airflow to go through the grooves to cool the tires. Tires are more prone to blowout while driving if the tread is shallow because there's no airflow, and the tires heat up to dangerous levels.
- Hydroplaning: Shallow treaded tires aren't as efficient at diverting water, which increases the risk of hydroplaning. Hydroplaning occurs when a layer of water is between your tires and the road, creating a slick surface and causing your vehicle to slide.
- Poor handling in mud, snow and ice: The sipes on your tires wear away along with the tread. Sipes offer increased stability and traction, giving you better control when driving on muddy, snowy or icy roads.
Wear and Tear
Uneven tire tread can cause damage to your vehicle's drivetrain or transmission, especially if you drive an all-wheel drive or four-wheel drive vehicle. You should ensure all of your tires are the same brand, size and tread pattern and have the same tread depth. That measure can help prevent excess strain on your vehicle.
Pennsylvania requires annual vehicle inspections. Your car won't pass an inspection if the tread is less than 2/32 of an inch or less than 4/32 of an inch on the front tires if your vehicle is over 10,000 pounds.
How to Tell if You Have Worn Tires
There are several signs you should be aware of that can indicate your tires are worn and need to be replaced:
- Vibration or thumping: Vibrations or thumping while driving may be a sign that a tire doesn't have an equal tread level compared to the other tires. A tire can develop a flat spot when wheels lock after using the brakes in an emergency. It would be best to have a mechanic rotate your tires every 5,000 to 8,000 miles to prevent the uneven tread from developing.
- Pulling to one side when driving: You may notice your vehicle pulling you towards the left or the right while driving. An underinflated or damaged tire often causes this, and you should have your tires inspected by a professional.
- Wear on the edge of the tread: If heavy wear on your tires occurs only on one edge, you may have an alignment problem or an issue with your suspension.
- Underinflation: Underinflated tires are more prone to faster wearing, especially around the edges. You should always ensure your tires are properly inflated to extend their lifespan. Worn tires are susceptible to punctures and tears that also facilitate air leakage.
- Erratic tread wear: Erratic tread wear means your tires have high tread in some areas and low tread in others. The cause may be linked to an out-of-balance wheel, worn shock absorbers or damaged suspension. You should take your car to a mechanic and have them identify and resolve the cause to extend your tires' lifespan and avoid additional wear.
- Sidewall cuts and tears: The most common causes of sidewall cuts and tears on your tires are debris found on roads or your wheel coming into contact with a curb. If the damage is severe, you may see cords that look like wires coming out of the tire.
- Bubbles or bulges: Bubbles most often form on the tire's sidewall or in areas where the tread has been worn very low. You shouldn't drive on a tire with a bubble or bulge and should have it replaced as soon as possible.
Overall, you should take your vehicle to an auto repair shop as soon as you notice anything unusual about how your car is driving or how your tires appear. A quick inspection at a mechanic could save you money and keep you safe in the long run.
Tire Tread Depth Chart
Monitoring your tires' tread depth is critical to ensure they're safe to drive on. These measurements determine whether the tread is still in drivable condition or if the tires need to be replaced:
- 4/32 of an inch or deeper: The tread is in good condition.
- 3/32 of an inch: You should continue monitoring the tread and have your tires replaced soon.
- 2/32 of an inch or less: You need to replace your tires as soon as possible.
Using the Penny or Quarter Test to Check Tires for Wear
If you're asking yourself, "How do I check my tires for wear?" you're not alone! This question is common, and there are several ways to quickly inspect your tires and ensure their tread levels are still safe. You only need one of two things to check your tires' wear — either a standard United States penny or quarter.
Penny Tire Tread Test
Do you have a penny somewhere in your car or wallet? If so, you can quickly check the tread on your tires to see if there's still a safe level of tread left. Follow these steps to do the penny tread test:
- Take a penny and turn it upside down so Lincoln's head is facing the ground.
- Place the penny onto your tire in several different grooves.
- Look for the top of Lincoln's head.
If the tire's tread covers a part of the head, there's at least 2/32 of an inch of tread remaining on the tire, and you should be okay without a replacement for now. If you can see the entire head, then your tread is less than 2/32 of an inch, and you should have your tires replaced as soon as possible.
Quarter Tire Tread Test
No penny? That's not a problem. You can also test your tread by using a quarter instead. These steps explain how to measure tire tread with a quarter:
- Take a quarter and flip it upside down so Washington's head is facing the ground.
- Place the quarter onto your tire into a few tread grooves.
- Look for the top of Washington's head.
If the tread touches the top of the head, then your tread has at least 4/32 of an inch remaining, and you're good to continue driving on the tires. If the tread doesn't obscure the head, then your tires will likely need to be replaced soon.
Other Ways to Check Tire Wear
If you don't have any spare change or are looking for additional ways to check your tire's wear, there are tools you can purchase and built-in safety features you can look for to identify excessive wear on a tire.
Wear Bar Indicator
Most tire manufactures include wear bar indicators built into tires. Take a look at your tires and identify rectangular bars embedded within the tire tread. They should be around your tire in several different locations. These bars are set at 2/32 of an inch, so if your tread is even with the bars, it's time to replace your tires. The bars exist to help you quickly monitor your tire tread and are an easy way to identify if your tires are worn out.
Tread Depth Gauge
A tread depth gauge is a tool you can buy at any auto parts store and is the most accurate way to measure a tire's tread. They're easy to use, and all you need to do is:
- Press the probe onto a ridge in your tire.
- Press the shoulders of the probe flat against the tread
- Read the measurement that's shown on the probe.
Most probes will measure in both millimeters and inches. If the reading is above 3/32 of an inch, your tires are still road-safe. If the measurement is 2/32 of an inch or less, you need to replace your tires as soon as possible.
Worn-out tires are big culprits of solo vehicle accidents. A membership with AAA offers the ultimate peace of mind by knowing we're just a phone call away from assisting you with any vehicle emergencies you encounter.
If your tires need to be replaced or your vehicle has other maintenance or repair needs, find a AAA certified service center near you. By going to a AAA approved auto repair facility, you'll get the best service by highly trained mechanics who pass our rigorous inspection process.
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