Tire tread has the capacity to affect your vehicle’s safety and performance while on the go. While you might not think about your tire tread every time you drive, it is important to check in every once in a while to ensure that your tires are in good working order. Ready to talk about tire tread depth? Let’s dive in.
The tread depth of the tire is a vertical measurement between the top of the tread and the lowest groove. In the U.S., tire tread depth is measured in 32nds of an inch. When tires are brand new, they have tread depths from 10/32 to 11/32.
In the United States, tires are required by law to have easily recognizable tread wear indicators. As the tire tread wears down, it eventually becomes level with the tread wear indicator. At this point, the tire should be replaced. It has too little tread left to provide traction. If safety weren’t persuasive enough, keep in mind that it is also illegal to drive with bald tires.
The minimum legal limit is 2/32 of an inch. This doesn’t mean that tires are perfectly safe if they have 3/32 left of tread. This is simply the limit at which you won’t pass your state safety inspection. Your tires become incrementally less safe as the tread wears down.
When it comes to safety, your tires are literally where the rubber meets the road. Sufficient tire tread depth is necessary for safe turning and braking.
Low tire tread depth can spell disaster for your drive, including:
If you live in an area where it rains or snows frequently, consider replacing tires when they reach 4/32 of an inch. With worn tires, you are at risk of hydroplaning on wet roads.
This is when the tire can’t channel the water through the grooves. The car rides along the top of the water instead of staying in contact with the asphalt. As such, the tires can’t respond to the steering system. If you have experienced it, you know how terrifying it can be. In icy or snowy conditions, low tread depth makes it harder to stop. You can also fishtail when accelerating or slide sideways when turning.
There are special considerations for driving in hot weather as well. If you are heading into summer and your tires are near the end of their lifespan, be aware that they wear down faster on hot roads.
Easy peasy. All you need to check your tire tread depth is a penny. Insert the penny with Abraham Lincoln’s head upside down. If the top of Abe’s head is showing, it’s time for new tires. Tamara shows you how to do it in this video.
Be thorough when you measure your tread depth.
Insert the penny in several places around the tire. It’s not uncommon to have uneven tread wear. Measuring in several places will compensate for this.
Having the proper air pressure in your tires is also critical. Tire air pressure is expressed as a number followed by PSI. This stands for pounds per square inch. 28 PSI means 28 pounds per square inch. It is a measurement of the force inside the tire applied to one square inch. You can check the recommended tire pressure for your car in your owner’s manual or on a sticker inside the driver’s side door. For most vehicles, it is around 32 PSI.
If your pressure is too low, your tires will wear out quicker. You will also get poorer gas mileage. This is because it’s harder for your engine to propel a vehicle riding on squishy tires. Low tire air pressure also results in a jerkier ride. Thankfully, there are plenty of easy ways to score a free tire pressure refill.
If you discover that your tires are too low, fill to the correct pressure. Don’t assume ‘more is better’. There are problems with overinflation as well. When a tire has too much air, it doesn’t have as much surface area in contact with the pavement. This makes it more difficult to handle. It also increases the risk of a blowout. At high speeds, a blowout can be deadly.
Since the early 1970s, the National Highway Traffic Safety Administration (NHTSA) and international counterparts were concerned about the dangers of low air pressure. They were seeking technology that could warn drivers. Evidence was mounting that underinflated tires were a factor in thousands of car accidents each year. At the end of the decade, the NHTSA was also motivated by the energy crisis. Tire air pressure affects fuel economy.
Tire pressure sensing technology became available in the 1980s and was first used by Porsche on the 1987 Porsche 959.
In the U.S., TPMS was federally mandated beginning with the 2007 model year.
There are two types of TPMS, indirect and direct. Direct pressure detectors are located on the tire stems. If the sensor detects a significant drop in pressure, it sends an alert to the engine computer—resulting in a dashboard warning light. The indirect type uses the antilock brake system to detect low pressure by measuring wheel speed. Tires revolve at different speeds depending on air pressure. The indirect method is less reliable and has been largely phased out among manufacturers.
At Chapel Hill Tire, we have been providing professional automotive service to North Carolina drivers since 1953. We help our valued clients choose the right tire and protect their tire investment with alignment and wheel balancing services.
Do you need new tires in Cary, Apex, Carrboro, Chapel Hill, Raleigh, or Durham? Our experts can help you find the right tires for your vehicle at the lowest possible price.
With our Price Beat Guarantee, you can ensure you are getting the best possible price on new tires in the Triangle. Schedule an appointment at one of our 10 Triangle-area service centers. We look forward to welcoming you to Chapel Hill Tire!
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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. 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.
In the United States, tire tread depth is measured in 32nds of an inch. New tires typically come with 10/32” or 11/32” tread depths, and some truck, SUV and winter tires may have deeper tread depths than other models. The U.S. Department of Transportation recommends replacing tires when they reach 2/32”, and many states legally require tires to be replaced at this depth.
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.
A simple way to check your tire tread depth is by using a tread depth gauge. You can find tire tread depth gauges at your local auto parts store. There are many models available, but an inexpensive simple graduated probe gauge will work just fine. All you have to do is stick the probe into a groove in the tread and press the shoulders of the probe flat against the tread block and read the result. All gauges should measure in both 32nds of an inch and millimeters.
Another indicator of worn out tread already lives in your tires themselves. Every performance, light truck, or medium commercial tire comes equipped with indicator bars (or wear bars) embedded between the tread ribs at 2/32”. They’re there to help you monitor tread depth and make decisions about tire replacement. Just look to see if the tread is flush with the indicator bars.
If they are, it’s time to replace the tire.
While the penny tire test does deliver on what it promises – indicating whether tread has reached the legal limit – it may not be the best indicator of whether your tires are safe for the road. Tire performance can diminish significantly before your tread hits 2/32”. Even though the law deems fit for safe driving may not prevent you from hydroplaning or losing control in rainy, slushy conditions. If you think your tires may be close to needing replacement, have them checked out by a licensed mechanic.
The tire tread is the outer part of the wheel that provides traction in all weather conditions. The protectors inevitably wear out during the operation of the car, the working height of the slope decreases. The residual tread depth should be periodically monitored and the set of tires should be renewed in time - this will reduce the risk of losing control of the car and save the car owner from fines from the traffic police.
nine0005 Tread wear rate depends on many factors:
Measuring the thickness of the tread layer will allow you to accurately determine the degree of tire wear and make a decision in time to replace them with new ones.
Different tires have different wear limits. Tread depth affects vehicle handling and road safety.
| According to Chapter 5 of the SDA, limiting norms for the height of the tread pattern have been established. For category M1 - passenger cars - as well as vehicles of categories N1, O1 and O2, the minimum allowable value is 1.6 mm. When using winter tires on snowy or icy surfaces - the limit is 4 mm. nine0006 |
Let us explain what categories of vehicles we are talking about:
N1 - vehicles intended for the carriage of goods, having a technically permissible maximum mass of not more than 3.5 tons;
O1 - trailers, the technically permissible maximum mass of which is not more than 0.
75 tons;
O2 - trailers, the technically permissible maximum weight of which is over 0.75 tons, but not more than 3.5 tons. nine0006
The traffic police officer has the right to measure the residual depth with a verified device. In case of a recorded violation, a fine is imposed on the car owner.
The new summer tire has an average tread depth of 7-8 mm. The service life of summer tires is usually 3-5 seasons with average mileage and moderate driving style.
| Residual height limitation by law is 1.6 mm. However, with a remaining outer layer of 3 mm, the machine is already difficult to control, grip deteriorates, and a safety hazard arises. nine0006 |
Do not wait until the critical value is reached. Make sure you change tires in advance.
Winter tires are used in severe weather conditions: low temperatures, icy conditions, on snowy road surfaces.
Worn elements make the tire ineffective on slippery winter roads. Accordingly, a more serious approach to the condition of the tire tread is needed.
Non-studded friction tire (velcro) with tread depth 8-9mm. A new studded model - from 9 to 11 mm, some firms produce a tread with a height of 12-18 mm.
| If the tread wear is up to 4-5 mm, the winter set of tires needs to be replaced. In addition, the loss of more than 50% of the metal spikes is also a reason to change the car's shoes. |
The average life of winter tires is 2-4 years.
Universal all-weather is used in a temperate climate both in winter and in summer, it is optimal at temperatures from +10 to -10˚C. This type of tire is not suitable for use in snowfall or severe frosts. SDA allows the use of all-season tires in the winter if there is a special marking:
| All-season tires last 3-4 years on average. |
You can estimate the remaining tread layer in various ways:
On some tire models there are special volumetric indicators in the form of jumpers. Check: if the tread layer is worn down to the level of the jumpers, the tire is not suitable for further use. nine0006
On the surface of certain types of tires, manufacturers knock out numbers of various depths. Depreciation is assessed visually - by the visibility of individual numbers.
With the help of measuring instruments: from a metal ruler, caliper, depth gauge to an electronic tread depth gauge.
Many motorists measure the remaining tread depth with a coin. Warning: this method of measurement is not accurate. It will not show you actual tire wear figures.
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Tire tread height should be measured at least at 6 different points, preferably at 9 or even 12: in the center and from both edges of the tread, at different points around the circumference of the tire. The measurement results at all specified points must match. If they do not match, then the tire wears unevenly. The driver should find out why this is happening. Some causes of uneven tire wear are low or high pressure in them relative to the regular one, suspension failure, extreme driving style. nine0006
Old tires have become unusable, the amount of tread remaining is approaching a critical line - no need to take risks, it's time to change your car's shoes. There is a great temptation to get by with small financial costs and purchase a set of used tires. Be careful!
Sellers advertise used tires as good or excellent condition. Do not be too lazy to personally measure the height of the tread layer. And remember: for winter tires, a residual tread depth of 4 mm is already 100% wear.
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When buying used tires with tires, it is important to remember that tires from different manufacturers and seasons initially have different tread heights (when they are new). And most importantly: the tires have, accordingly, different wear limits - the tread depth at which the tire begins to lose important characteristics. These differences are most noticeable in winter and summer tires. Keep these points in mind when measuring the remaining tread depth of used tires.
The quality of domestic roads, unfortunately, does not allow tires to be used for 7-10 years. If you still decide to buy a used kit, check the year of manufacture - it is better not to consider tires older than 8 years. nine0006
there is no guarantee for tires bought from hands;
the seller can cheat - for example, offer tires from different manufacturers in one set. Some especially enterprising salesmen even cut the tread on the worn rubber, as if the tires had not yet worn out;
you will have to spend a lot of time picking up tires from private sellers - much of what is put up for sale is only suitable for recycling; nine0006
Products may have hidden or visible defects.
Visible are punctures, tears, cuts. A tire with a lot of damage can collapse in motion. Hidden defects include damage to the cord, which most often occurs after punctures or a strong blow. A car with such a malfunction may wiggle on the road, and it will be unstable;
the goods were stored in the wrong conditions, for example, under direct sunlight - this reduces the life of the tires and they will quickly become unusable, even if the residual tread depth is ideal; nine0006
it is not always possible to carry out a tire fitting in the presence of the seller, you will have to check the kit yourself after payment.
Without a specialist, there is a risk of buying tires that you cannot use. Don't skimp on safety. Purchasing a new set of tires will require more investment, but will pay off with a long period of trouble-free operation.
The maximum permissible residual tread depth for a passenger car is 1.
6 mm in summer and 4 mm in winter. nine0006
SDA strictly regulate the residual height of the tread pattern. Violation of traffic rules is a reason for drawing up an administrative protocol.
For your own safety, replace worn tires on time. Better for new ones.
In fact, the average life of any tire is 5-7 years, but a lot depends on how the owner treats his car. Aggressive driving, improper seasonal tire storage, unrepaired suspension/balancing problems, incorrect pressure and other errors can significantly shorten tire life. But worn tires can be a serious problem on the road: an increased risk of uncontrolled skidding, hydroplaning, even accidents is the price that drivers and passengers have to pay for using old tires. nine0006
Each manufacturer indicates the so-called wear index on the tire profile, which most often looks like the inscription “Treadwear 100” and means a maximum of 48,000 km on a standard road surface (polygon).
In a real environment and often not the most ideal roads, this number actually needs to be divided by 1.5 - we get 36,000 km.
By analogy, if the wear resistance index is 150, then this means “factory” 72 thousand km, 200 - 96 thousand km., and so on.
What are the dangers of worn tires on the road:
adhesion to the roadway deteriorates, which leads to an increased likelihood of skidding, accidents, hydroplaning in case of rainy weather;
reduced cross-country ability in off-road conditions;
increases the risk of a tire puncture while driving. nine0006
It is also worth remembering that the issue of tire wear is regulated by traffic rules, and you can get a fine for using “bald” rubber. Knowing what maximum tire wear is acceptable, this is easy to avoid: 1.5-2 mm for summer, and 4-5 mm for winter (a more accurate figure is indicated by the manufacturer).
1.
According to the wear indicator on the tire. To find this indicator, you need to inspect the side of the tire and find one of the markings: a triangle, a company logo, a snowflake, or the abbreviation TWI. If the tread has worn down to this indicator, it means that the tire needs to be disposed of urgently. nine0006
2. Many people in the old fashioned way prefer to use a 10-kopeck coin. Insert it into the tread with the inscription "10 kopecks" towards you, and if it is visible, the wear level is too high, you need to replace the tire. This method is convenient, but not entirely accurate: by measuring wear in different parts of the tire in this way, it will be difficult to estimate its unevenness by eye, and this is also an extremely important indicator.
3. It is optimal to use a special gauge, depth ruler or caliper for these purposes. This will allow you to measure the wear of the tread in different parts of the tire with an accuracy of up to a millimeter and understand if there is uneven wear.
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If measurements show different results in different parts of the tread, it is important to determine exactly how your tires wear in order to understand where and what the operating error is.
If the tread wears more on the sides and the center wears off less, this means that the tire pressure is insufficient and the contact patch with the road is not correct. This leads not only to poor vehicle stability, but also to increased fuel consumption. nine0006
If the tread is worn down the middle but the sidewalls are fine, then your tires are overinflated. Sometimes this is done intentionally in order to save fuel, but in this case, the tires will still have to be changed ahead of schedule.
There is also the possibility of increased wear on the inside or outside of the tread - this indicates an incorrect camber. A visual table with wear options and their causes:
Cracks on the sides of tires can indicate frequent off-road driving, improper storage, low-quality rubber or long service life, as well as incorrect tire pressure.
Bulges or "hernias" on the sides of the tires appear as a result of the side part hitting hard obstacles. Tires with such damage are not recommended. nine0006
Dents on the tread indicate insufficient depreciation and unadjusted camber. Having found such damage, it is necessary to drive the car to the service and make sure that the suspension is in good condition.
Individual wear spots on the tread indicate aggressive driving / braking, skidding with wheel locks, or prolonged parking of the car in one position. nine0006
Most often, this is required for the sale and purchase of used tires in order to orient the buyer in the degree of their wear. Many sellers give this figure at random, but this method has nothing to do with the actual assessment of the degree of tire wear. It is also important to understand that a conditional 50% wear for a summer tire is an acceptable value, while 50% wear of a winter tire tread is a sign that the tire cannot be used.
Therefore, it is important to know how to accurately determine the percentage of tire wear so as not to get into an unpleasant situation. nine0006
Many people divide the actual tread height by the height of the same, but new tire, and get a certain percentage of wear. This would be correct, if not for one BUT: we cannot physically erase the tread to zero, and the law prohibits the use of tires with a tread below the permitted values.
You can calculate actual tire wear by dividing the difference between the new tire height and the actual tire height by the difference between the new tire tread height and the minimum possible tread height for that tire, and then multiplying this number by 100. nine0006
If it is impossible to find out the height of the same, but with a new tire, use the average values of your tire type:
| Tire type | Average tread height at start of use |
| Winter tires with Scandinavian tread | 10 mm nine0006 |
| Winter with regular or asymmetric tread | 9 mm |
| High-speed winter | 7 mm |
| Summer tires with classic tread nine0021 | 8 mm |
| Summer speed | 7 mm |
You can check summer tires for wear a little less often than winter tires, since in summer the tread depth is not so important for patency.
In summer, at high temperatures, all-weather tires wear out much faster. It is recommended to buy new tires when the tread layer is abraded to a value of 2-2.5 mm. 
