Tire Tread and the Useful Penny Test
Anyone who drives a car knows what tire tread is. But do you know how to tell whether it’s wearing thin?
Worn out tires affect your car’s performance and your safety. Luckily, there’s a simple way to check your tires with just your pocket change.
Measuring Tread Depth With the Penny Test
A new car tire typically has a tread depth of 10⁄32 or 11⁄32 inches while a light truck will have between 11⁄32 and 19⁄32 inches. The U.S. Department of Transportation recommends that you replace your tires once they’ve worn down to 2⁄32 inches. Many states require tires to be replaced when the tread reaches that depth.
How do you know when your tires are officially worn out? You can use a tread depth gauge or take your car in for a professional evaluation. But the easiest way is to do a penny test.
- Take a penny and place it with Lincoln’s head upside down between two ribs on your tire.
- If part of the head is covered, your tires are still in good shape.
- If you can see his entire head, your tread is worn to 2⁄32 inch or less and it’s time for new tires.
- Check various points on the tire — around the circumference and between different ribs — to look for uneven tire wear.
Many car and truck tires come with indicator bars at 2⁄32 inch. If these are even with your tread ribs, you’ll know your tires need to be replaced.
Now you can measure your tread, but you may not know about all its components or what different tread patterns are for. The more you know about types of tread, the easier it will be for you to choose the best tires for your vehicle. Here are some facts to beef up your tire knowledge.
What Is Tire Tread?
There are four (sometimes five) main components to tire tread:
- Ribs: The long, raised bands that go all the way around a tire.
- Blocks or lugs: The raised segments between ribs.
- Grooves: The space between ribs.
- Voids: The space between tread blocks.
- Sipes (sometimes): Thin slits cut across the tread blocks and ribs.
Ribs and tread blocks make contact with the pavement, while grooves and voids channel water when roads are wet and allow the blocks to flex as tires grip the road.
Siping is designed to improve tire performance during wet and winter driving conditions.
Different tire manufacturers combine these features to create signature designs and offer good performance for a range of driving conditions.
Types of Tire Tread Patterns
Though each tire manufacturer makes unique variations on tire tread, the patterns generally fall into three categories. Each pattern provides different handling and performance.
- Symmetric designs, as the name suggests, have the same pattern across the whole tire. This is the most common tread pattern for passenger cars.
- Directional tread patterns include lateral voids pointing in only one direction, making a V design, and are used on performance cars (those designed for speed). These tires channel water in one direction for reliable handling in wet conditions and provide zippy handling on dry roads.
- Asymmetric designs combine the above two patterns to offer good grip on dry roads as well as traction in wet and winter conditions. The inner side of the tire often features lateral voids like those found in directional tires, while the outer side uses larger tread blocks.
Summer tires and winter tires both generally have a symmetric design, with winter tires sporting deeper tread depth and sipes. Asymmetric patterns are often a good choice for all-season tires.
Safety Risks of Worn Tires
Though tires are considered bald at 2⁄32 inch, they lose some of their performance capabilities before that.
As tire tread wears, it becomes less able to channel water and the risk of hydroplaning increases, especially at higher speeds. If you know your tires are partly worn, be sure to give yourself extra stopping distance in wet conditions.
Grip loss on snowy or icy roads is a concern. As the rubber wears, sipes disappear and tread blocks don't provide as much grip. Again, allow yourself more stopping distance and consider replacing your tires to stay safe during winter months.
Tires with partly worn tread are more likely to get punctures and lose air pressure, too. And punctures can cause tire failure, which is a particular problem at high speeds because you can lose control of your vehicle.
Drive on Safely
A penny test will tell you when your tires are bald, but if you’re headed into winter or a rainy season, a tread depth gauge is the surest way to test. Or stop by your local tire shop to have a professional evaluate your tires.
How Long Will Your Spare Tire Last?
The tires on your car or truck are designed to tackle miles of pavement, gravel, dirt, and all sorts of weather conditions. But every so often, you’re going to run over an object that could cause a flat tire. When that happens and you install your spare, how long can you drive and still make it safely to the tire shop? We have some answers to help you save money and stay safe on the road.
Your Spare is NOT a Long Term Solution
According to most vehicle manufacturers, a temporary spare tire (also known as a donut spare) should only be used to get from where you discovered your flat tire to the nearest tire repair shop. While there are different sizes and types of spares, we suggest you keep speeds at or below 50 miles per hour and drive no more than 50 miles on a spare tire before getting your flat fixed. Some full-size spare tires, or spare tires that are designed to match the other 4 tires on the vehicle, can be installed and used for longer distances, at normal speeds. Since these spares may not be used often, just make sure the air pressure is set to the manufacturer's specification, and the tire doesn't have any visible issues before hitting the road. If there are any concerns, proceed with caution or seek advice from a tire professional.
Why? Because your temporary spare tire may be smaller than your everyday tires. This makes it spin faster than the rest of the wheels. Plus, the tread can be vastly different, or the tire may not be designed for long distances. Regardless, those differences can decrease your control, reduce stopping power, cause hydroplaning on wet roads, and can damage your transmission and other parts of your vehicle. See your owner’s manual or the side of your spare tire for recommended safe driving speeds and distances.
Les Schwab Tip: Whether you drive a handful of miles every day or hundreds of miles a week, it’s important to learn how to change a tire. It’s easy and can save you from paying and/or waiting for roadside assistance.
What is a Space-Saver Spare?
Also known as a donut spare, the space-saver spare tire was designed to save space in smaller vehicles. If you drive a compact or smaller vehicle, you may have a space-saver spare. These tires have less traction than your regular tires, are smaller, should not be driven at speeds over 50 miles per hour, and should not be used for more than 50 miles. That’s enough to get you to your nearest Les Schwab Tires for a free flat repair when you have our tires on your vehicle.
What is a Full-Size Spare?
Many vehicles, including sedans, SUVs and larger trucks have a full-size spare. As the name implies, they are the same size as the other tires on your vehicle. However, the tread on the spare may be different. If there is far more tread on the spare, you may notice decreased control and comfort while driving. And if the spare has minimized tread, you could experience hydroplaning on wet roads or reduced stopping distance. Either way, it’s a good idea to get to Les Schwab when you have a flat. That way you can reduce your time driving on a spare.
What are Expandable/Inflatable Spare Tires?
Expandable/inflatable spare tires are available in some vehicles, including Porsche, Audi, Volkswagen, Mercedes, and Ferrari models. These spares come with a non-inflated tire mounted to the rim and an air compressor. Once you inflate and install the spare, it’s ready to get you to the nearest Les Schwab.
What About Run-Flat Tires?
You may wonder if you even need a spare tire at all. The answer is maybe. Run-flat tires are designed to withstand punctures and remain mostly inflated. However, if you do begin to lose tire pressure, these tires need to be inspected and repaired quickly to avoid a full replacement.
Les Schwab Knows Tires (and Spares)
The distances between tire service can be long. Spare tires, as well as run-flat tires need attention, just like your regular tires. Not sure what kind of spare you have or if it’s even properly inflated? Schedule a Les Schwab free pre-trip safety check. We’ll give everything a visual inspection and show you what to do the next time you get a flat.
A Helpful Q&A Guide to Buying Tires
A lot of people choose tires based on the mileage warranty and cost. However, these are only two of many important factors to consider.
There are lots of choices between tires even at the same mileage and price point. It’s important to understand key factors to have the right tire for your driving needs. Things to ask about are: tire size, performance rating, load rating, ply rating, expected mileage and tread design, so you can depend on your tires and feel safe while traveling.
Here are answers to questions people ask the most about how to pick out tires. This info won’t make you a tire expert but will give you the basics when you visit your tire dealer.
Q: Do I Want All-season or Snow Tires?
A: It depends on whether you drive in winter conditions regularly.
Tires are categorized as all-season, summer, traction, winter or highway (for light trucks). Buying a set of highway or all-season tires is a good choice if you live in a sunny, warm climate that gets occasional rain and you aren’t regularly traveling on snow and ice. They perform well in climates where temperatures don’t typically get below 45 degrees. All-season tires are built to handle hot pavement but don’t offer the traction needed for slick, winter roads. If your area gets snow or ice every year, or if you make regular trips over mountain passes in the winter months, you’ll likely need all-season tires for spring, summer and fall driving, and snow tires for more harsh conditions. Get the full lowdown on how they’re different and how to choose winter tires.
Q: Do I Want Performance Tires?
A: Performance tires are designed for better cornering and handling at higher speeds. If these are your priorities, talk to your tire dealer about your options.
Other specialty tires, such as traction tires for pickups and SUVs, are for off-roading, gravel and driving in mud.
Sometimes your demands are simple; you just need a quiet, smooth passenger car tire for freeway driving. All-season or all-terrain tires are made to handle year-round driving needs on and off the blacktop. A good tire dealer will ask you the right questions and know the best product for your needs and budget.
Q: Does Driving Winter Tires in Summer Damage Them?
A: Yes. With more people running studless winter tires, this is a growing issue. Winter tires are made with a special rubber compound that stays softer and more pliable in cold weather for better road grip. As seasonal tires, they aren’t designed to handle the heat. All-season tires are made with a different rubber compound suitable for hot pavement.
If you use winter tires in hot weather they are going to wear out much quicker. It’s important to factor in the long-term cost if you’re thinking about running your winter tires through the warm months. This could reduce their life by years.
Q: Is There Really a Difference Between Higher- and Lower-priced Tires?
Tire pricing is typically based on what the tire delivers for comfort, ride quality, noise level, tread durability and traction features. Some tires for specific uses. For instance, light truck mud tires may have a higher price point because they have more rubber on them, which increases the cost to produce them. Prices also reflect the value you can expect from your tire; tread life typically ranges from 30,000 to 80,000 miles. This mileage can vary depending on whether you are looking at passenger car, performance car, light truck or SUV tires.
Q: Who Makes the Best Tires?
A: There are plenty of well-made tires. The biggest differences often come down to the warranty. Most of what you get in a tire warranty is provided by the dealer, not the tire maker. If there’s a defect in the tire you buy, that’s covered by the manufacturer. However, many other warranty features are covered by the dealer that sold and installed your tires.
Tire service warranties vary greatly by dealer and can be worth hundreds of dollars over the life of a tire. A well-built tire is only as good as the warranty backing it, so consider everything that’s in the warranty. Here’s a list of what to look for:
- Length of coverage. The best warranties extend for the full life of the tire’s tread mileage guarantee, not a set number of years.
- Workmanship. Both the tire and the quality of installation/repairs should be covered.
- Free care. Whether flat repairs, regular inspections for wear, tire rotations and rebalancing are free.
- Road hazard coverage. If you hit debris or a pothole and the tire is damaged beyond repair, is the value of the tire covered?
- Convenience. How many locations honor the warranty.
Be careful about buying extended tire coverage, like tire certificates, which replace your tires for free if you ruin them. It’s very rare to damage multiple tires beyond repair over the life of the tires. Usually, damage to a tire can be repaired and often it’s a single tire that’s involved. By the time you add up the cost of covering your tires with certificates, you could pay for any tire that gets damaged.
There are other drawbacks as well. Tire replacement certificates often expire after three years. And some aren’t honored if the damage comes from running your tires at the improper inflation.
Q: Can I Change My Tire Size?
A: Swapping out your tires for bigger or smaller ones than what came new on your vehicle is a fun way to change your ride’s look. Understand that it may affect performance. Be aware that when you change to a taller tire, your speedometer will read slower than you’re going because your tire is spinning fewer revolutions per mile (RPM). You may get more road noise and differences in the way your vehicle handles.
In contrast, lowering the profile of your car or truck by using a smaller tire size will alter both handling and how much clearance you have. You may bottom out on hills that you used to clear just fine and it may stiffen the ride.
You can use a tire size calculator to see how different sized tires will affect your RPMs and tire speed, but such tools are only estimates.
Be sure to cover all the unknowns by talking with a tire professional before you change sidewall height or tread width. An expert will know how to translate the difference in RPM, tire speed, load index and speed rating into what it will mean for your vehicle and driving. They’ll also explain how the tires or wheels you have your eye on will or won’t fit with your vehicle’s suspension, gearing and bodywork.
Q: Is It Ok to Replace One Tire at a Time?
A: It’s best to consider replacing tires in pairs, but read your owner’s manual. Even small size and type differences between your four tires can have big consequences, especially if you own an all-wheel drive (AWD).
Replacing one tire with a different brand, model, size or tread depth can cause a noticeable pull in the steering wheel or other handling issues. There are tight tolerances for AWDs, so they’re at greater risk for such problems.
A big difference in tread depth between tires can damage expensive parts. It is always a good idea to review your owner’s manual to see if the vehicle manufacturer has a point of view on this.
Q: Will Buying Tires Online Save Me Money?
A: It might save you some money if you’re a tire expert and have a place that will mount the tires on your wheels. If not and you don’t, you run the risk of getting the wrong type of tires for your vehicle and driving. Then that Internet bargain can add up to a lot more hassle, time and money than expected.
Another issue is finding a tire dealer that will service your tires by mounting and balancing them on your wheels at a reasonable cost. This can get expensive if you’re changing out summer and winter tires twice a year. Here are some cost and warranty factors to consider when you’re thinking of buying online.
Have other questions than what we’ve covered? See more answers in our Tire FAQ or find your local Les Schwab store to talk to a pro.