What does speed index and tire load index mean?

Automobile tires are the most affected by external factors. They are acted upon by a constant force from the vehicle’s mass, when coupled with the road surface, the ramps are subjected to mechanical, thermal, and in winter chemical attack from various reagents. Additionally, different driving conditions also affect wear, especially if you do not take into account the speed index and tire load index during operation.

Information about the conditions in which the manufacturer recommends using their tires is applied to the side of the wheel. In the form of coefficients and letter markings, the manufacturer informs customers about the permissible characteristics and modes of operation of the wheels.


  • 1 Tire load index
  • 2 Load Index Table
  • 3 Additional power characteristics
  • 4 Installing tires by load index
  • 5 Explanation of the speed index
  • 6 Markings for speeds
  • 7 Linking speed index with load index
  • 8 Conclusion

Tire load index

Считается, что этот параметр больше интересует водителей грузовиков. Они чаще обращают на него внимание, так как индекс нагрузки на шинах означает допустимое максимальное значение усorя, которое разрешено на одно колесо. Информация отображается в килограммах.

A higher indicator of this index shows that in the manufacture of rubber increased requirements were applied to the material, and allowed to provide the best stability of the car during the movement. Strengthening the construction of the slope in this case leads to a more severe rubber reaction to all the irregularities of the road. This is a payback for the opportunity to lift the load.

which means the speed index on the tires means

In order to avoid the roar of the wheels, you need to use rubber with a low index. The driver will be able to take less cargo on board, but it will provide greater smoothness of the car’s travel and reduce the load on the suspension and other structural components. Thus, if you adhere to the parameters established by manufacturers and understand what a tire load index is, and also know how to choose the right rubber with it, will ensure safe and comfortable driving auto.

Load Index Table

In tire production, компании руководствуются общепринятой классификацией по нагрузкам. Для каждой покрышки установлен максимально разрешенный вес, который она сможет выдержать. Индексы рассчитаны на массу от 45 килограмм до 33,5т на одно колесо. Минимальный числовой индекс «0» разрешает нагрузку до 45 кг, а максимальный «230» говорит о допустимом значении 33500 кг.

what the speed index and tire load table look like

Tire load index table

Such data is usually combined with speed indicators, and the result is a table of tire speed and load index. However, in practice for cars there is no need for a large number of values ​​from such a database, because it is hard to imagine a full-fledged car weighing 45x4 = 180 kg with the index “0”. It's more like some kind of car. Also on the road you will not see a car 33500x4 = 134000 kg and the index "230". The conditional parameters are relevant for career vehicles, not sedans. In reality, information remains in demand from the “golden mean” of such a table approximately from the index of the fifth dozen to the beginning of the first hundred.

See also: DIY repair of tubeless tires: instructions for using a special set

Для транспорта, использующего спарку шин, например, автобусы or грузовики в маркировке указывается значение через «дробь».

You need to know that manufacturers are laying in the characteristics of the permissible load the possibility of short-term data exceeding by 20-25% of the calculated value.

Однако, не стоит выбирать скаты для авто слишком «впритык» по значениям. Специалисты рекомендуют воспользоваться формулой для выбора нагрузки на одно колесо: вес машины поделить пополам и добавить 10%. Соответственно на машину массой 1000 кг понадобится выбрать покрышки с индексом «87» or «88», а расшифровка такая: (1000/2)+10%=550 кг.

Additional power characteristics

Load index is a complex concept. With it, you can calculate the possible amount of cargo. In this case, do not forget the total carrying capacity of the car.

where speed index and tire load index are written

Various tire sizes

As data, which give a complete picture of the power characteristics of the tires, applied layer labels. In the international classification, the concept is denoted Ply Rating or abbreviation PR. The bearing capacity of the entire tire carcass directly depends on this quality.

You need to know that rubber, which can withstand significant pressure under dynamic loads, is able to work with a significant carrying capacity.

Common features for passenger cars are 4PR or at six. Products labeled at six or at 8 в большей степени подходит для установки на микроавтобусы or грузовой транспорт малой и средней грузоподъемности.

The international designation is accepted to designate the increased load index Reinforced. On wheels, you can find his abbreviated ways of writing in the form Reinf or RF.

The reinforced version of tires may contain in the designation the letter "C" (commercial). Often this symbol stands after the designation of the diameter of the wheel.

Max Load manufacturers set for information about limit weights. After this code, the allowed mass is written either in kilograms (kg) for countries with a metric system, or in pounds (lbs), more often for the Anglo-Saxon market.

Installing tires by load index

You should not complete the car with tires with the load parameter indicated on them lower than the manufacturer recommends. This leads to significant wear on the rubber surface during operation. It is especially important to use the right tires on a bad road. A safety factor appears here, because a weak wheel can not withstand the load if it hits a hole sharply and burst.

how to find out the speed index and tire load index

Interpretation of tire marking

Скаты с относительно небольшим запасом прочности разрешены к установке. Они могут иметь маркировку при прочих равных условиях RF or XL.

Calculating the load on the wheels, you need to take into account the uneven distribution of the mass of the car. The front part with the motor must withstand the weight of the power plant, so the slopes must be selected for the axis under the engine with a small margin of safety.

See also: How to determine tire wear

Explanation of the speed index

According to the European standard ECE-R54 each tire on the front side must be marked with acceptable working conditions. In such data weights and speed limits are indicated. Information is applied in the form of speed and load indexes.

During operation, you should not exceed the limits set by the manufacturer, since due to the amplification of centrifugal forces, resonant vibration occurs, which can lead to dire consequences. The specified speed index on tires means the maximum allowable value of the vehicle speed with such tires.

Speed ​​markings

The marking for the speed index is adopted universal and represents the letters of the Latin alphabet, corresponding to a certain limit. Such data is entered in the speed index table. For example, one of the most common parameters “H” indicates the highest permissible speed parameter at 210 km / h.

how the speed index and tire load index are labeled

Types of tires

The table of values ​​starts with the marking “A”, corresponding to a maximum of 40 km / h. However, such parameters are unpopular for passenger cars, therefore, in practice, symbols from “J” limiting movement of 100 km / h to “Y” corresponding to 300 km / h are used.

In tire production companies invest a small margin of safety for their productsbut practice shows that you should not rely on the design characteristics and bring the car to the maximum permissible speeds. Especially such experiments are fraught for domestic roads. It is preferable to use the resource at 80-90% of the calculated value.

Read more about tire marking features.

Linking speed index with load index

Those who want to figure out what the tire speed index is, you need to know, ISH is closely related to the load index. This is especially important for high speed limits from the bottom of the table.

what the table contains the index of speed and load of tires

Speed ​​index table

For example, in the 90T marking, speed parameters up to 190 km / h and a wheel load of 600 kg are encrypted. However, by increasing the speed, the driver increases the dynamic force on the tires. As a recommendation, you can use the ratio: speeding at 10 km / h should be offset by a 5% reduction in weight. The discrepancy between these parameters can lead to rupture of the tire during movement.

The company or the country of origin has no influence on the speed index. It is necessary to pick up slopes for your car according to the recommendations indicated in the car’s instruction manual. Also, the softness of rubber directly depends on the speed index: the higher the index, the lower the stiffness, which means better grip, but higher wear.


Speed ​​indices and tire loads must be taken into account when driving a car. On compliance with these parameters depends not only on the quality of operation of rubber and the car in general, but also the safety of the driver and passengers. Prolonged exceedance of standard design values ​​for speed and load can lead to a breakdown of ramps. The recommended maximum values ​​for operation in both parameters are 90% of the specified standards for rubber.