How to tell if tires are worn


How To Tell If You Need New Tires

Every year in the U.S., tire-related crashes cause 200 fatalities, according to the National Highway Traffic Safety Administration. Thankfully, it’s easy to monitor your tires, and how to tell if you need new tires, with a quick video and some basic information.

5 Warning Signs You Need New Tires

The primary functions of the tread on your tires are to grip the road and to divert water that causes hydroplaning. Tires with plenty of tread can help you maintain control and reduce your chances of getting a flat. With a quick monthly check of your tread and tire pressure, you’ll know if you need to replace your tires.

Tread Wear Bars are Flush with the Tread:

Tread wear bars are small, raised bits of rubber that run between the tread blocks. As these bars become even with the top of the tread, it is likely time for new tires. See more about tread wear bars below.

Cracked Rubber:

Tires will wear down over time, even if you don’t drive much. Sunlight, heat, and chemicals used to melt snow and ice can reduce rubber flexibility, causing tires to crack, lose air, and eventually fail.

Uneven Tire Tread:

There are many factors that may cause uneven wear, which could shorten the life of your tires. Vehicle alignment, tire pressure, lack of rotation, and/or worn steering and suspension components can all contribute to this problem. To prolong the life of your tires and reduce uneven wear, consider getting them rotated at consistent intervals. At Les Schwab, we recommend getting them rotated every 5,000 milles. The pros at Les Schwab will also conduct a free visual inspection of your steering and suspension components. Schedule your free, pre-trip safety check today.

Tire Pressure Issues:

All tires deflate slowly over time, usually about 1 PSI (pounds per square inch) per month. Check yours monthly to keep them properly inflated. If your tires continually lose air or seem to completely deflate without warning, you may need to stop by Les Schwab for tire repair or replacement if necessary. Does the TPMS (Tire Pressure Monitoring System) light often appear on your dash? This could mean your tires have developed a slow, continuous leak.

Sidewall Bulges:

If you hit a curb, pothole or other obstacle, your tires can develop sidewall bulges due to a break of the inner liner. These bulges can rupture causing a potentially unsafe situation. If you spot a bulge on your tires, get to your nearby Les Schwab and have your tires inspected.

Other Possible Issues:

If you experience new vibrations or thumping while driving, it could be a sign that one of your tire/wheel assemblies is out of balance. It could also indicate a suspension issue. Stop by your local Les Schwab and our professionals will check your tires, steering, and suspension.


Easy Ways to Check Your Tread


Use the Tread Wear Bars

All tires sold in the United States today have what are called tread wear bars. The tread wear bars on your tires are there to help you see how much tread you still have. These wear bars are small, raised bars of rubber in the grooves of your tire. Look at the tread pattern and you’ll see these bars running between the tread blocks.

How do I use them to diagnose worn tires?

Look at the tread pattern and you’ll see these bars running between the tread blocks. As your tires wear, these bars will become increasingly flush with the tire’s tread. It’s important to replace your tires before this happens.

Depending on where and how you drive, and the conditions you face on the road, you might consider getting new tires before they reach that point. City driving in mild conditions may allow you to wait until the tread is closer to the tread wear bar before replacing your tires. More adverse conditions, such as rain, snow, and unpaved roads, may require you to replace your tires earlier.


Do the Penny Test

An easy way to check the tread on your tires is to do the penny test. Take a penny and place Lincoln’s head in one of the grooves of the tire tread. If you can see all of Lincoln’s head, it’s time to replace the tire.

If the penny goes in enough that the tire tread is at least as deep as Lincoln’s forehead, your tires are generally considered safe and do not need replacing. Check all four of your tires when conducting the penny test.


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With this easy test, a penny can buy you peace of mind when it comes to your tires and safety.

Place a penny head first into several tread grooves across the tire. If you always see the top of Lincoln’s head, your treads are shallow and worn. If this is the case, your tires need to be replaced.

If part of Lincoln’s head is always covered by the tread, you have more than 2/32 of an inch of tread depth remaining. This means you probably don’t need new tires.

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 in 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:

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

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I need new tires

When it’s time to change your tires, your Firestone Complete Auto Care dealer wants to make purchasing a new set as simple as possible. We have the best selection of quality tires to fit your vehicle, your budget and your driving style. From economy to ultra high performance tires - in the size you need from brands you trust, including our well-known Bridgestone and Firestone brands - you can find what you need right here.

Make a selection from the following options:

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How to determine the wear of summer tires

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.

Tire wear index

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.

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).

3 ways to determine tire wear

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.

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.

Uneven tire wear: how to determine the causes, what is dangerous

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.

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:


How to assess tire wear visually: additional parameters

  • 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.

  • 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.

How to calculate tire wear percentage

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.

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.

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

Winter with regular or asymmetric tread

9 mm

High-speed winter

7 mm

Summer tires with classic tread

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.

If you have assessed the condition of your tires on all of the above factors and realized that the tires are worn out, be sure to replace them with new ones as soon as possible.

Tire wear - how to determine tire wear


Many items undergo wear, but due to the frequency of use, it is most noticeable on tires. Every motorist at least once faced with such a problem. Finding a solution is very simple - just buy new tires. But next time it is important to determine why this happened.

A lot depends on the speed of traffic, air temperature, road surface, tire pressure, vehicle load, etc. There are many factors that affect tire wear, but these wheel elements lose their original appearance during long-term operation in any case. True, if you properly handle rubber and know all the nuances, you can extend its shelf life.

The most common causes of tire wear are:

  • gradual aging of the rubber coating. It depends on the conditions of use and storage of tires. Improper operation and storage in sunlight, in a warm or cold, damp room exceeds the allowable wear;
  • one-sided abrasion. In this case, the rubber can wear out from the outside, tire wear from the inside is not ruled out;
  • use of tires with incorrect pressure;
  • malfunctions in springs, levers, shock absorbers;
  • tire and wheel imbalance;
  • Emergency braking or long standstill may cause a defect.

Types of wear

In general, rubber wear can be divided into two types:

  • normal wear, when the rubber has worked out all its purpose;
  • premature, which causes many of the above reasons.

If normal wear can only be said that the life of the tires has deservedly come to an end and you need to buy new ones, then with regard to premature wear, the following types are distinguished:

  • damage to the central part of the tread;
  • hernia on sidewall;
  • rubber cracks;
  • wear on the edges of the tread, this is often the case for trucks;
  • flat spot wear;
  • uneven wear on one side.

All about uneven wear

Tires often go bald after a couple of thousand kilometers. This is the first sign of uneven wear, which experts call patchy. Most often, he talks about the low quality of rubber, problems with the car, or the inexperience of the driver. Slip starts, hard braking and aggressive driving can kill any tire. Even if there are winter tires, the car can fly off the road. You can correct the situation if you replace the rubber or adjust it on a special stand at the service station.

There are three main causes of wear:

  • lateral rotation force;
  • drawing;
  • physical and chemical composition.

Tires wear out both on the inside and on the outside with increased pressure, fast braking and inept driving. If the wear is uneven and one side has worn more than the other, then the tires can be swapped, but this action should be performed by a professional. The best way to correct the situation is to contact the tire service.

What are the dangers of driving with worn tires?

Each driver decides for himself whether to ride on bald tires or buy a new one, but it's better not to risk your own life and the lives of others. It is recommended to regularly diagnose and monitor the condition of the tires.

Worn tires can lead to accidents at any time of the year and in any weather. Thinking that good tires are needed only in ice is a mistake. A worn out tread does not provide proper grip even with high-quality road surfaces in dry weather. In the rain, the behavior of the car is generally unpredictable. Hydroplaning on bald tires can lead to an accident.

Difficult to brake with bald tires, especially on slippery surfaces. A strong turn of the car, unexpected turns can lead to an accident. Most often, these situations happen to those who do not conduct timely diagnostics and do not buy new high-quality tires. It is important to note that the average life of any rubber is 5 years.

How to determine tire wear?

The driver must regularly check the wear. Such tires very often puncture, slide on water, lead to an accident, reduce braking and stability on the track. The total wear limit is 1.6 mm.

The following methods of determination are distinguished:

  • the use of a special wear indicator;
  • profile depth measurement.

Tire wear indicator

The best and most popular way to measure tire wear is with a wear indicator, which is usually located deep in the longitudinal grooves. Each tire model has its own tread depth, which must be checked using special methods, because when this depth wears out, it becomes dangerous to drive on wet, slippery or icy surfaces.

How can uneven wear be determined?

Using technical tools, the fastest and easiest way to determine the depth of wear of rubber. This requires a special device. This device can be purchased at any service station or auto parts store.

How to use the special wear gauge?

It must be placed directly in the tread groove and then switched on.


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