- How to determine rubber wear
- Why pay attention to wear
- Car tire life
- What makes tires wear out faster
- Types of tire wear and their causes
- Methods for checking wear
- Permissible tread wear of summer and winter tires
- Formula for calculating wear
The most important point to look at in order to understand that tire wear has become critical and it is time to change them are the wear indicators that tire manufacturers carefully place at the bottom of the tread grooves. Typically, tire brands calculate the minimum residual tread depth based on how well the tire maintains its performance, such as speed and water removal from the contact patch.
Ignore timely tire replacement strongly not recommended, as it depends on them safety of people in the car.
The shallower the residual tread depth of the tire, the worse it removes water from the contact patch and, accordingly, the higher the risk of aquaplaning. Wear close to the maximum allowable will not allow you to feel confident in turns, and on gravel and dirt roads, a weak hold will appear.
Why pay attention to wear
Every part of the machine wears out to one degree or another and needs to be replaced over time. In the case of car tires, their quality not only affects the safety of passengers and the driver in a given car, but also of other road users.
Monitoring the condition of your tires is part of your vehicle's routine maintenance. An attentive motorist periodically checks the oil level in the engine, the amount of coolant, the health of the brake system, and also the lighting fixtures.
The depth of the drawing is inextricably linked with such factors:
- Vehicle handling. The lower the height of the pattern, the less dirt and water will drain away, and this increases the risk of losing control of the machine when driving through puddles. When cornering on dirt roads, the vehicle may skid due to poor grip.
- Braking distances. The worn tread reduces the grip of the tires, even on dry asphalt, which increases the braking distance under the same operating conditions.
- Uneven wear of the sipes may indicate some vehicle malfunctions, for example, wheel imbalance or the need to adjust the wheel alignment.
Car tire life
Most manufacturers set a maximum life of ten years. However, this figure is relative. Here are the main factors affecting the suitability of automotive rubber:
- How the tire was stored;
- Under what conditions it was operated;
- Natural aging.
The shelf life is the period set by the manufacturer during which the tire does not lose its properties. This period begins from the moment of manufacture, and not from the date of purchase. This information can be found on the side of the tire. It looks like four numbers. The first two indicate the week, and the rest indicate the year of manufacture.
For example, buying a "new" rubber that has been in a warehouse for four years, you can use it for no more than six years (if the warranty period is limited to 10 years). Even if it was stored correctly, rubber tends to age, which is why microcracks appear on it, and it loses its elasticity.
It is also worth considering that different types of tires are created for winter and summer operating conditions. There is also a third type - all-season. Some motorists use it to save money.
For example, the owners of front-wheel drive cars "shoe" the rear wheels in such rubber so as not to buy a complete set of winter and summer ones. In fact, experienced drivers do not recommend carrying out such "experiments", since the "universal" version has a smaller resource, and is not as reliable as the model for a particular season.
In the manufacture of automobile tires, to increase their elasticity, manufacturers add rubber to its composition (in addition to additional substances that affect the quality of products). This polymer acquires different properties at different temperatures:
- at -70 degrees begins to crystallize;
- becomes fluid at + 180-200 degrees;
- at +250 rubber breaks down into gaseous and liquid substances.
Since in the summer the temperature of the air and road surface exceeds the value of +10 degrees, less rubber is added to the composition of tires than rubber.
Due to the increased rigidity, such tires are more resistant to wear than winter ones. The tread in it is not as deep (usually 7-8 millimeters) as in the winter version, since its main task is to drain water and dirt from under the wheel. For winter options, it is important that snow does not linger between the lamellas, so the pattern in them is deeper and wider.
In addition to these characteristics, you also need to focus on your driving style preferences. For a measured mode, some characteristics of tires are required (pattern, stiffness, depth and width of the pattern), for sports driving with sharp maneuvers - others, and for offroad - still others.
Summer tires are not as noisy as winter tires. Over the entire period of operation, they experience less stress due to temperature changes (it is warm in the garage in winter, and frost on the street), as well as due to a sharp change in the quality of the road surface (in winter, snow may be present on the road during one trip, ice, water).
Due to these characteristics, the service life of summer tires practically corresponds to that declared by the manufacturer.
Here is a short video test of summer tires:
The first difference between winter tires and summer tires is their elasticity due to the increased rubber content. Without this polymer, rubber at low temperatures not only loses its plasticity, but also begins the process of its glass transition. Because of this, the usual stress during a quiet ride can be fatal for summer tires if it's freezing outside.
Since the car often drives on snow-covered road sections in winter, winter tires need a deeper tread with wider sipes. Thanks to this, the pattern is not clogged with snow, and the tire "clings" not to a soft layer of snow and mud, but to a harder surface. These characteristics are very important not only when cornering, but also when driving uphill.
Here is a comparative table of how the efficiency of winter tires changes in the case of different tread depths (for example, tires 185/60 R14 with different degrees of wear are taken):
|Winter, tread 8 mm.||Winter, tread 7,5 mm.||Winter, tread 4 mm.|
|Braking on dry asphalt,%||100||106||118|
|Braking on wet asphalt,%||100||103||93|
Taking into account the elasticity of the material, the tread in this type of tire wears out faster than that of its summer counterparts. Although manufacturers often set the same service life for both summer and winter tires, the latter recommend changing when passing:
- passenger car (up to 2000 kg.) 40-45 000 km;
- truck (2-4 tons) 60 km;
- truck (over 4 kg.) 000-65 thousand.
Look also at the rating of winter tires (2019):
What makes tires wear out faster
There are factors that affect the rate of tire wear. Only the observance of ideal conditions will allow maintaining the quality of automobile rubber within the limits set by manufacturers, but this is rarely achieved. Here's what leads to premature wear:
- Non-compliance with storage conditions. You can save tires with and without disks, only the conditions will be different. Tires with discs can be either suspended or laid on their side. Without discs, tires can only be stored upright (not suspended). The room should be well ventilated, the sun's rays should not fall on the rubber (special covers can be used), it should not be too damp or too dry in it.
- Incorrect pressure. When the pressure requirements are met (often these recommendations are placed by automakers on the B-pillar on the driver's side or on the inside of the gas cap), the tread will wear evenly. Riding on inflated or flat tires shortens the interval between buying new sets.
- The quality of the material. Budget models often fail after about two seasons of operation, and branded ones last longer - four, and sometimes seven.
- The quality of the road surface. Sharp gravel, sharp-edged pits, bumps, etc. creates an uneven excessive load, which leads to deformation of the rubber.
- Riding style. Sharp acceleration and braking, driving at high speeds, sharp turns - all this can reduce the working life of tires.
- Frequent overload of the machine. A heavy load moves the center of gravity to the rear of the vehicle. Frequent operation in this mode will not only require replacing the rear tires, but can also lead to damage to the suspension elements.
Types of tire wear and their causes
A problem in some parts of the car may affect the condition of the tread. This indicator also sometimes signals that the car is being misused.
This information will help determine what the driver is doing wrong or when a specific malfunction appears in the car. It will also come in handy if you decide to buy used tires. Below are the main types of wear and what they indicate.
Evenly worn tread indicates that the tires have been properly stored. This also serves as an indicator of the correct tuning of the car's chassis. In addition to wear, it is also important to pay attention to the presence of microcracks.
It indicates that the car is driving on over-pumped wheels. Since the rubber has become stiffer due to the increased pressure, the wheel adheres to the road only in the central part.
This type of wear is typical for running on flat tires. In this case, the contact patch moves to the edges. The stiffening ribs are loaded, and the rough road surface does its job.
This type of wear is typical for vehicles with incorrectly set axle geometry. If the tires wear off more on the inside, then this indicates a negative camber. External wear is a sign of positive camber.
Low-quality rims can also be a problem. Under strong impacts (a hole with sharp edges, a border, etc.), it can deform, but outwardly it may not be noticeable.
This wear is most often indicative of improper wheel balancing. If balancing does not help to fix the problem, you need to take the car to a service station for a suspension diagnosis. Levers may be defective or damper struts.
Uneven on each single axle pair
It happens that the left tire is more worn out than the right (or vice versa). Most likely, this means that when buying new cylinders, the owner of the car did not look at the date of their production. Tires from different batches may wear differently. If this is not the reason, then the wheel alignment should be checked.
For driving on loose and very wet soil, special tires are created - "alligator" or "button". They are characterized by a block pattern with rounded sides. Sawtooth wear may appear on these tires. This happens due to frequent travel on poorly paved roads.
Also, this problem appears when the wheel toe angle is incorrect.
In addition, watch a video overview of common types of wear and how to fix them:
There are several ways to check the suitability of tires for further use. Let's consider the most popular ones.
The minimum residual tread depth of summer and winter tires is 1,6 mm. Manufacturers usually position their indicators of permissible wear at this height with small tolerances in the larger direction. You can measure the depth of their location using a special depth gauge or ruler. In the second case, the value may not be accurate.
Finding these indicators is easy enough. They are located at the bottom of the grooves of the tire tread pattern, and on the sidewall they are marked with a special TWI marking. Somewhere this marking may look like an inscription, someone marks it with a triangle, and some manufacturers even draw pictograms with their own logos.
Some tire manufacturers use a special system of numbers - indices, which helps the driver to determine the level of rubber wear. Today, there are three main types of digital indicators:
- With a number of numbers from 2 to 8. Marking is carried out in millimeters.
- Segmented, in which numbers are squeezed out in one place at different depths. With wear, the value changes to indicate the degree of wear.
- With a number of numbers. This marking is made as a percentage of the tread height.
To determine tire wear in this way, no additional tools are required. Everything becomes clear at one glance at the rubber.
Interesting method definitions wear and tear of tires, which came up with Chinese designers. It involves a discoloration of the tire, depending on the degree of abrasion. Gradually, the tread color changes from black to bright orange.
This is a device that allows you to measure the depth of the tread grooves. Depending on the modification, it can be either mechanical or electronic. Checking rubber wear with a gauge is considered the most correct, as it allows you to "point" inspect each suspicious section of the tire.
These devices are widely available on the market and are inexpensive. You can buy a tread depth gauge at almost any car dealership or on the Internet.
Permissible tread wear of summer and winter tires
According to the legislation, the critical depth of the pattern for summer tires is 1,6 millimeters, and for winter tires - 4 millimeters.
In addition to this limitation, there are some amendments for different types of vehicles (summer tires):
|Vehicle type:||Limit wear value, mm.|
|Passenger and low-tonnage cargo||1,6|
For wide profile summer tires, the specified minimum value is 1,6mm. too little, so experts recommend replacing it with a residual tread depth of 3,0 mm.
Do not wait for the rubber to wear to a minimum. This increases the risk of increased braking distance on wet roads and aquaplaning, since the tread is no longer efficient in removing water from the contact patch.
Formula for calculating wear
To accurately calculate tire wear, you should rely on more than just the residual pattern depth. The percentage of this indicator will show whether it is worth buying a certain used model or it is better to dig up and purchase a new kit. This indicator is calculated using the following formula:
Z = (Amax-Anow) / (Amax-Amin) * 100%
Z is the percentage of wear on a particular tire.
Amax is the initial height of the picture. This indicator can be found in the description of the characteristics on the manufacturer's website. If such information is not available, then you can focus on the average value. For summer tires it is 8 mm, and for winter tires - 9 mm. (cross-country model - 10 mm.)
Anow is the current height. This figure is obtained by measuring the depth at 6-10 different points. The minimum value is substituted into the formula.
Amin is the minimum allowable value for a specific modification (table above).
This formula will help determine the remaining tire life.
See why you shouldn't wait for the tread to wear down to the minimum allowable value:
Although every driver should constantly monitor the height of the pattern, it is worth paying attention to the service life of the product (it is up to 10 years). Even if the tread has not had time to wear off during this time, the rubber loses its properties. Its elasticity deteriorates, becomes brittle, cracks and oxidizes. In this case, replacement should be carried out at the end of the service life.
Timely maintenance of the chassis and suspension of the car, the appropriate pressure and correct seasonal storage will help to extend the life of the tires during active operation of the car.
In conclusion, we offer a short video on what can be dangerous buying "new" rubber on your hands: