Each tire in its own marking except geometric parameters characterizing the width of the tire, the size of its sidewall and the landing diameter, has load and speed indices, which reflect some technical features tires.

Load index

Load index for car tires expressed, as a rule, by a two- or three-digit number, which in the marking goes immediately after the bore diameter. It can also be called the “tire load capacity index” and means the maximum load capacity for which the tire is designed during operation.

Each size for a passenger car, according to ETRTO standards (European Tire and Rim Technical Organization - European technical organization rims and tires), can have two load indices assigned to it -standard and increased. So, for example, a size 205/55R16 might have a load index of 91, which allows one tire to carry a load of 615 kg, or 94, which equals 670 kg per tire.

Increased load index

Increased load indexin the tire label necessarily accompanied additional designation- XL, extraload or reinforced.

Such an additional marking of increased load capacity is often interpreted by drivers as an increased strength indicator of the tire, i.e. a tire marked XL (extraload, reinforced) has a stronger sidewall. However, this is just a common misconception and an increased load index does nothing to protect the tire from sidewall tear or tread damage in service.

Marking features

It should be borne in mind that ETRTO fixes tire parameters for European market. For North America there are other standards, they are similar in many ways, but the North American ones have some features.

For example, a Latin letter can be added to the beginning of the marking "P"(the initial letter in the word “passenger” is passenger), which can mean that the tire uses a load index less than the standard one:

When choosing a size with the letter “P” at the beginning, you need to check the technical documentation of the car and see if it can be used on it. reduced load index.

Dual load index

In addition, now you can find another designation that complements the load index and came from the North American market -LT("lighttruck" - light truck or pickup truck). It is also added to the beginning of the size and indicates that this size has an increased load index, expressed as a double number.

Example: LT265/65 R17 120/117S.

This special double load index markingmeans that for vehicles with four wheels on two axles, the tire load is calculated according to the first, largest index. And if the car has six wheels with two axles (double tires for the rear axle), then you need to take the second, smallest index.

Example:

For standard car with tire size LT265/65 R17 120/117 S you need to take the index 120 - this is 1400 kg per tire, and Weight Limit, which can carry such a car, will be equal to 1400 x 4 \u003d 5600 kg.

For a vehicle with dual tires on the rear axle and tire size LT265/65 R17 120/117 S, you need to take the index 117 already - this is 1285 kg per tire, the maximum weight is 1285 x 6 = 7710.

Thus, a car with dual tires on the rear axle will be able to carry more weight even using the smaller of the indexes in the tire size.

A similar use of dual load index sizes is found in the ETRTO standards for tire sizes intended for use on vans or small trucks mobiles (weighing up to 6 tons). But in this case, it is accompanied by the Latin letter "C" (commercial - commercial) and looks like this: 225/60 R16 C 105/103 T.

Speed ​​index

Speed ​​index(or speed category) is a conditional indicator that indicates the maximum speed that a tire can withstand. Speed ​​indices are indicated in Latin letters from A (minimum, A1 = 5 km/h) to Y (maximum, 300 km/h). For passenger cars mobiles the following common speed indices can be distinguished:

Standard : T(190km/h), N(210km/h)

high speed: V(240km/h), W(270km/h), Y(300km/h)

And commercial tires tend to have lower speed ratings: Q (160 km/h), R (170 km/h), S (180 km/h).

Winter tires, depending on the type, can have a small speed index Q (160 km/h, for studded tires) and a fairly high W (270 km/h, for non-studded tires). winter tires Central European type).

Some high speed tires have a speed index with a category even higher than that indicated in the tire size. For example, size 325/25ZR20 (101Y ), where the speed index looks like this - ZR (Y), allows you to reach speeds of over 300 km / h.

Speed ​​index not specified

Sometimes you can meet tires, where speed index not specified. This has happened in the past, but with latest changes in the technical regulations, tires without a speed index (and, as a rule, without a load index) were banned from sale in the territory of the Russian Federation.

Why were such tires produced in the past?

Some sports cars received specially prepared tires that could be installed exclusively on this sports car. In this case, already at the development stage, tire engineers calculated and incorporated into the tire maximum weight sports car, and the speed index was limited only by the maximum speed corresponding car. And there was no need to indicate the speed and load indices, since the formula “special tire - only for one special vehicle". With the development of the segment sports cars such "uniqueness" disappeared and could mislead a potential buyer. Therefore, it was decided to provide each tire size with a corresponding speed and load index.

Choice of speed and load indices

Given that the load index is "attached" to the size, the consumer, choosing the tire size allowed for installation, automatically receives the necessary load index. In some cases, you need to check technical documentation to the car, whether you need a size with an increased load capacity (XL, extraload, reinforced) or immediately opt for the allowed sizes with a large load index. Moreover, some tire manufacturers(e.g. MICHELIN) already produce most tires in sizes with higher load capacities.

The situation is more complicated with the speed index. According to current technical standards, the driver must choose summer tires to replace those that were installed on the conveyor with a speed index not lower than the original equipment.

For example, you cannot select a tire with a speed index of T (190 km/h) to replace a tire with a speed index of H (210 km/h), but you can choose a high-speed tire with a speed index of V (240 km/h), W (270 km /h) and above.

Tire load index- an important parameter that you need to pay attention to when choosing car tires. The tire load index marking is located on the sidewall of the profile and is indicated as a numerical value. What does the tire load index mean? For example, 215/65 R16 98T, the number "98" indicates that the load capacity or load index of the tire is 750 kg.

Tire load index table

The designation of the tire load index is indicated in the marking by a combination of numbers. The tire load table below shows all load index values ​​according to their symbol.

Tire load index Explanation table

For passenger cars, a rubber load index from 60 to 125, or in other words, from 250 kg to 1650 kg, is used. This range includes both small cars and large SUVs.

What does the maximum tire load index mean?

The maximum tire load index (maximum tire load in kg) means that the tire can withstand a certain load at the maximum allowable speed, which is marked as a maximum tire speed index.

How to calculate the tire load index for a car?

For a correct calculation, the load index indicated on the tire must be multiplied by the number of tires of the car (usually 4), subtract the curb weight of the car and the weight of the driver with passengers from the resulting value. As a result, the resulting difference will be the value of the free load capacity of the car. In other words, you will get the value of the weight that can be placed in a car without compromising safety when driving at a speed determined by the speed index of the tires used. Let's look at a specific example of how to calculate the tire load index for a car.

For example, tires 215/65 R16 98T, where 98T is the load and speed index marking. Load index "98" corresponds to a load capacity of 750 kg per wheel. We multiply 750 kg by the number of wheels (for example, 4), we get 3000 kg of total load capacity. Now, from 3000 kg we subtract the weight of the car (for example, 1500 kg), the weight of the driver (say, 90 kg) and, for example, 3 passengers with a total weight of 200 kg, we get a difference of 1210 kg, the potential weight of the load that can be evenly placed in the car without reducing the level of safety when maximum speed "T" index of 190 km/h.

The load index is the maximum permissible value, to which it is better not to approach when operating the car. It is necessary to take into account the fact how exactly and where the cargo will be placed in the car. As a rule, the most popular place to place cargo is in the trunk, with the main load on rear axle or in other words, on 2 wheels. Based on this, you need to calculate the maximum weight of the cargo in the trunk. How to calculate the bus load in this case? In the example above, the maximum weight of the cargo for the car turned out to be 1210 kg, but if you load the trunk, then the maximum possible weight of the cargo will be at the level of 600 kg, and for safe movement- no more than 450 kg. If the load index is as close as possible to or exceeded, tires can wear out faster and deform under shock loads on rough roads. Using the maximum possible load, relative to the load index, at the maximum possible speeds, relative to the tire speed index - NOT SAFE!

Tire load index interpretation

Deciphering the tire load index is only possible thanks to special tables, such as "Tire load index decoding" () or with the help of consultants from car tire stores, who should provide any information of interest on the product offered. Choosing suitable tires, it is necessary to pay attention to the fact that the higher the tire load index from the manufacturer's recommended auto, the less ride comfort remains, due to the increase in rigidity and the strengthening of the sidewall of the tires to withstand the weight determined by the load index. Underestimating the wheel load index recommended by the auto manufacturer is also not worth it, in this case, the comfort of movement will be greater, but the level of passive safety will decrease.

Each tire in without fail has a tire speed index. The interpretation of this designation is reduced to limiting the speed of the car with a maximum load. The main task of labeling is to maintain balance. The parameter is closely intertwined with the lifting coefficient.

Generalization of the term

European standards ECE-R54 require the presence on the visible part of the tire court of the designations "Service Description", which means - a characteristic of operating conditions. Indices of speed, load capacity are located near the marking of the tire dimension.
Failure to comply with the limit prescribed by the tire manufacturer is fraught with an increase in influence centrifugal forces, as a result - the appearance of resonance in the form of vibration of the wheel in the direction of the car.
Example: wheel marking 185/65 R14 86H. Information in the form of numbers related to speed is expressed by the letter "H" (limited to 210 kilometers per hour).

Designations and explanations to them

There is a specially designed information scale (decoding) that corresponds to the main characteristics of the tire. Designations in it: English letters coupled with numbers. But a number of markings speed index does not carry any ordinary motorist useful information, so the most popular indexes are selected below.
Decryption:

• "J" - speed limit: up to 100 km / h;
• "K" - up to 110;
• "L" - up to 120;
• "M" - up to 130;
• "N" - up to 140;
• "P" - up to 150;
• "Q" - up to 160;
• "R" - up to 170;
• "S" - up to 180;
• "T" - up to 190;
• "U" - up to 200 tons;
• "H" - up to 210;
• "V" - up to 240;
• "VR" - more than 240;
• "W" - up to 270;
• "Y" - up to 300 tons;
• "ZR" - over 240 km / h.

In this way:

• J- lower limit speed;
• "Y" - upper;
• double designations "VR" / "ZR" - it is allowed to exceed valid index speed.

Tire speed index and tire load index table

1. It is not recommended to exceed the indicated limits.
   In the production of tires, the manufacturer, for the purpose of reinsurance, indicates an underestimated speed limit. However, even he should not be approached often.
   Recommended high-speed operation of a tire for cars and trucks- no more than 90% of the declared maximum. This is especially important when long trips, and winter operation. More detailed information contained in the characteristics of a particular tire model.
2. Using tires in winter
   Winter operation requires the use of snowflake-marked tires, and letters"M+S" (M&S, M/S) - mud/snow conditions. However, not every tire with these letters is winter.
3. Temperature
   Use not recommended winter wheels if the air temperature for a long time is + 7 ° C or even higher. In this case, the soft composition of the tire quickly provokes its accelerated wear and a decrease in the tread depth (studs falling out)
4. Close relationship between load factor and speed
   The load capacity coefficient (load index) of tires is a designation in the form of numbers of the maximum permissible load that the tire will withstand at an indexed speed and a certain air pressure in the tire.

The load limits indicated do not indicate a tire rupture in case of exceeding the speed index. You can deviate from the limit by another 15-20%.

A certain load factor interacts with a corresponding maximum speed factor. There are a number of tires (speed marking: Y, V, W) for which you need to reduce the load factor. Whereas tires "ZR", for example, are deprived of such a condition. In this case, it is necessary to obtain information on the maximum permissible load from the manufacturer of these tires.
As a result: the closer to the maximum speeds, the less load should be on each wheel. It is also necessary to monitor the pressure in the tire - it should be within the limits recommended by the automaker.

Choosing the right load factor

Often, the weight distribution along the axes of most cars is uneven. Therefore, it is necessary to buy tires whose ratio will be about 20% higher than the gross vehicle weight.
A higher load indicator provides a high smoothness of the machine due to the thick tire carcass. The main thing is not to overdo it, because rubber with a too high coefficient indicates a hard tire, which will provoke a deterioration in driving comfort and a decrease in the life of the chassis. The optimal indicator is about 30% of the total curb weight of the car, no more.

It is unacceptable to use tires whose load rating is less than that specified by the automaker for a particular car brand. Otherwise, installing tires with a low load indicator may result in their rupture by high speeds.

When buying tires, motorists rarely consider the numbers and letters that are indicated on the product. AT best case the buyer pays attention to the diameter, width of the rubber, tread pattern and, of course, the price. But to choose quality rubber This is not enough. It is important to pay attention to all the numbers and letters printed on the product. Do not forget about deciphering the tire speed index - a parameter that many people forget about.

How are tires marked?

1. Tire manufacturer. Everything is logical here. The development company wants to distinguish itself from the general mass of other products, to push a person to buy. This is especially true if the brand is well-known, for example, Continental, Michelin, Pirelli and so on.
2. Tread type and model. Manufacturer's instructions are not everything. Each brand has a whole group of models that differ in their characteristics, pattern features, speed index, and so on. For example, Michelin has such models as Pilot Sport, Pilot City and so on. At the same time, sports tires can be immediately distinguished by soft tread corners, and highway tires, on the contrary, by more rigid ones. At the same time, different models the composition of rubber, pattern, tread type, and so on may differ.
3. Tire size is one of the main parameters. Here the profile width (in mm), profile height (percentage of the tire width) and seat size are indicated. For example, the designation may look like this - 140/80-16 (140 mm is the width, 80 is the height or 80% of the width, 16 is the inner bore diameter). At the same time, there are options. If the size name looks like 195 R14 C 104 Q (for example), then this indicates a complete tire profile. In such cases, the ratio of height to width is 80-82%. At the same time, 195 is the width of the tire, R14 is the diameter, C is the “reinforced” tire, 104 is the load index, Q is the speed index.
4. Tire type - chambered (TT) and tubeless (TL).
5. Tire production date. As a rule, this designation has the form of three or four numbers on the side of the product. For example, 1207 may indicate that the product was made at week 12 in 2007.
6. Design indexing. Two options are possible here - diagonal and radial.
7. The speed index shows the maximum speed for the tire (we will discuss this parameter in more detail below). To understand this term, it is necessary full transcript tire speed indexing.
8. Tire load index - characterizes the maximum weight on one or another part of the car, which is permissible for a tire.
9. Additional marking. It can indicate which part of the car the wheel should be placed on, the direction of rotation, the tests passed, and so on.

Tire marking

What is the tire speed index and how does it stand for?

The speed index displays the speed at which it is recommended to drive a car “shod” in specific tires. Exceeding the specified parameter is prohibited. As a rule, the speed index indicator is not indicated as a number (as many beginners believe), but in literal terms. Finding the designation on the tire is not difficult - it is located on the side of the tire next to its size.

It is not difficult to determine the specified parameter and the maximum speed limit. To display the index, Latin letters are used, starting from A to the letter Z. In this case, the first letter A displays the lowest speed index, and the letter Z, on the contrary, the maximum. As a rule, the following designations are found on modern tires:

1. Letter "J". When installing such tires, the speed should not exceed 100 kilometers per hour. Otherwise, the manufacturer does not give any guarantees about the integrity of the rubber.
2. The letters "M", "L" and "K" signal the speed limits of 130, 120 and 110 kilometers per hour. At the same time, it is not recommended to drive at a higher speed on tires with such markings.
3. The letter "N" makes it possible to move at speeds up to 150 kilometers per hour. For many trucks, this option is one of the most preferred.
4. Designations in the form of letters "Q" and "R" signal the maximum speed limits, limited to 160 and 170 kilometers per hour.
5. Tires with the letters "S" and "T" are made in such a way that they can withstand speeds up to 180 and 190 kilometers per hour, respectively.

If we are talking about a sports vehicle that can accelerate great speed, then the tire speed index should be appropriate. In particular, it will require the installation of tires marked "U", which allows you to move at a speed of 200 km / h, and higher. At the same time, rubber is being sold today, which allows you to drive a car at speeds up to 300 km / h. In this case, the index is expressed by the Latin letter "Y".

On a number of products, deciphering the tire speed index causes certain difficulties. For example, many beginners are confused by the presence of two-letter designations. All that changes in this case is the allowed upper and lower range. For example, the designation "VR" allows you to move at any speed up to 210-300 kilometers per hour. If the marking "ZR" is applied, then this allows you to accelerate the car to 240-300 kilometers per hour.

There are situations when there is no tire marking in relation to the speed index at all. In this case, it is considered that the maximum speed should not exceed 110 km / h.

Speed ​​index and load index - what to consider

In addition to the specifics +, it is necessary to take into account a number of important points:

The speed index and the load index are two parameters that are closely intertwined and should be evaluated as a whole. The load index is usually specified in relation to the upper limit of the speed parameter. At the same time, the permissible load parameter itself directly affects the nature of the transport movement and the tire resource.

If the load index has a small parameter, then the car will move with less noise, but the tire will wear out faster. Conversely, if the load indicator is high, then the rubber will be noisier, but will last longer.

In addition, if the speed limit per tire is 200 km/h, then in case of exceeding given parameter at 10 km/h it is necessary to reduce the load by an average of 3%.

So, if you bought tires with a maximum allowable speed at 180 km / h, and you plan to drive at a speed of 210 km / h, then the load must be reduced by 9%.

1. Exceeding the maximum allowable speed parameter is prohibited.
2. When buying reinforced tires, it is necessary to focus on the parameter of the speed index that is written on the tire and confirmed by the tests carried out by the manufacturer.
3. On demand international standards tires for passenger cars, as a rule, have an identical load parameter. At the same time, the speed index is in the range from 180 to 240 km / h.
4. To extend the life of the tire, you need to buy products with a small margin of the speed index - an average of 10-15% higher.
5. To avoid problems on the road (in particular, accidental tire burst when driving on increased speed) it is necessary to give preference to products with more high index speed. The main thing is not to overdo it. If you put tires with a clearly overestimated parameter (for example, rubber for sports cars on ordinary cars), then ride comfort will suffer.
6. If the set of tires has different speed limits, then stiffer tires should be placed on the front tires. In this case, the wear of the four tires will be more or less uniform.
7. The year of manufacture or country of manufacture of the vehicle does not affect the speed index parameter in any way.
8. Tire seasonality and speed limits are dependent on each other. For example, for winter tires the speed index must be at least "H".
9. The greater the speed index parameter, the greater the softness of the vehicle rubber. As a result, the quality of adhesion to the road increases significantly. Outcome - more rapid wear tires.

Video: Tires. Tire marking. Summer tires. Winter tires. Tires and wheels

Conclusion

Thus, every motorist must remember the importance of the parameters that are printed on the vehicle's tire. At the same time, it must be remembered that the safety and comfort of movement depend on the correct decoding of the tire speed index and the load index. That is why it is so important to pay attention to these aspects when buying.

It's normalized speed mode, within which the bus is allowed to be used. It is applied to the side car tire index in the form of letters of the Latin alphabet. The index is marked with one letter, which corresponds to the certified operating speed of tires of this type.

Tire speed index. Guises

The tire speed index is directly related to the load index. This is a numerical representation of the magnitude of the load that the tire is designed for at its nominal value. Important: All load indexes are relative to the maximum speed index value.

Tire speed index in action

Only those tires should be installed on the car, the tire speed index of which exceeds the minimum index specified in the car documentation. In some countries, drivers are obligated to affix in a conspicuous place a special label indicating the tire speed index. this car. While this set of tires is on a vehicle with a nominal index, the specified speed must not be exceeded.

Tire selection according to speed index

Everything car tires have the appropriate tire category and speed index. It's no secret that when choosing tires it is necessary, first of all, to pay attention to the information provided on the tire itself. Before purchasing a new set, you should decide in advance which type of tires will be the most acceptable and what should be the value of the speed index. The tread pattern determines the existence of the following types of tires: all-weather, summer, winter. for each type is determined based on the characteristics of the car.

Characteristics of tire types according to the speed index

Winter tires are traditionally marked with the tire speed index "H" and index "M+S". Picture winter tread is more pronounced, and the index designation corresponds to the same "H". All-season tires have characteristics that perform well in both dry and wet road conditions. Summer tires, on the other hand, are distinguished by the absence of a micropattern and more high rates grip and tire speed index.

Tire speed index as part of the size

The standard size is the generally accepted tire designation system. Usually it looks like this: 185/42 R15 75U. From the indicated marking it follows that 185 is the tire width, 42 is the ratio between the profile height and the width, R is a symbol that the system with radial cord, 15 - tire diameter, U - tire speed index equal to 200 km / h, 75 - load index. You can't go wrong with your choice if you follow the tire speed index given in your vehicle's documentation.

What is tire load index?

The tire load index is a numerical expression of the maximum load that any tire can withstand at speeds indicated by the corresponding index, as well as a certain air pressure in them. It should also be noted that such a load does not mean at all that if these indicators are exceeded, the tire can be torn to pieces. It is quite acceptable that it is exceeded by about 20-30%. It is worth noting that each load index is indicated for maximum speeds: for class Y tires, this figure is 270 kilometers per hour; for class W tires - 240 kilometers per hour and for class V tires this indicator reaches 210 kilometers per hour. Above listed indicators maximum index tire loads must be reduced. Certain tyres, and in particular ZR class tyres, do not include a description of these operating conditions. In such cases, it is recommended to contact the manufacturers to determine the maximum load values.

Tire load index marking in Europe

In accordance with the established European regulations, namely ECE-R54, absolutely all tires that are designed for commercial Vehicle, must be marked with the designation "Service Description", which means "Operating conditions". This marking applied next to the tire size designation. Such a marking is a specific code that shows the maximum value of the tire load index, as well as speed. This indicator includes the tire load index for twin and single wheels, as well as the speed index, for example 102/100R. Tire load and speed indices are applied to both sidewalls of each tire. The first number shows the load capacity of certain tires when installed alone, and the second one corresponds to dual wheels. Additional markings may be used to indicate corresponding tire loads at other higher speeds. Additional tire load index markings are always circled.

Tire load index, speeds and seasonality

At its core, the tire load index refers to the carrying capacity. This parameter is important for cars that are very often heavily loaded. To understand the load index of tires, their high-speed loads and seasonality, it is necessary to understand the markings on the tires themselves well. Near the size on the side surfaces of the tires indicate the indexes of loads, speeds, and in some cases indicate the seasonality of the tires. In addition, if the word “TUBELESS” is on the tire, this means that the tire can be beaded onto a rim without tubes.

How to choose the right tire load index?

The choice of tire is a very important issue for every car owner, because from the correct this choice the safety of car passengers and the car owner will directly depend. Each motorist can independently choose the right tires for his car, regardless of what year he is, in which country he was produced and what his carrying capacity is. In order to choose the right rubber, it is necessary to take into account a large number of very important parameters, such as driving style, driving conditions (off-road, highway or city), driving season, as well as the technical characteristics of the car itself. Tire load index denotes the maximum specific gravity of the car, which can only fall on one wheel. Here you need to understand a few important things: not always the weight of cars can be distributed evenly between the rear and front axles. Therefore, when choosing tire load indices for a car, it is necessary to make a small margin compared to a quarter of the total loaded mass of the car; the higher the tire load index, the less elastic it will be due to the greater thickness of the carcass. In turn, this will affect the possibility of better cushioning of pits and other irregularities. pavement. Therefore, it is necessary to take into account the fact that a rather large margin of safety will lead to a less comfortable ride on any car and, as a result, will accelerate the wear of the car's suspension. Thus, the most optimal tire load index for is indicators that approximately correspond to 30-35% gross weight cars.

Importance right choice tire index

It is very important that the tires must withstand the appropriate loads that will meet technical specifications individual car. Maximum loads, which a certain rubber can withstand is determined in relative units, indicated on the tire bead and can vary from 60 to 125 units. It is worth reiterating that tire load indexes are per wheel. For trucks, the tire load index indicates one wheel or paired tires through a fraction. When choosing tires, the load index is one of key indicators. Such a small digital designation hides the maximum permissible load for each wheel that the tire can support while driving on maximum speeds. It must be well remembered that each value of the indices corresponds to certain loads, expressed in kilograms.

Wrong choice of tire load index

In no case should rubber be installed on cars, which is less than indicated in basic configurations certain manufacturers. However, it may be possible to install tires with a slightly higher load index. For example, it can be a tire with an RF index - Reinford or XL. At wrong choice and an insufficient load index, the consequences can be sad, because the tires simply cannot withstand such loads. Of course, the tire may not break on the way, but troubles cannot be avoided. It must be remembered that there are certain norms for the fluctuation of the tire load index, which must be strictly adhered to.