How to determine the tire load index in the marking of car wheels? Seeing an unfamiliar tire for a car, at first glance to understand what this product is - this is not an easy task. In reality, everything is much simpler than it seems at first glance. For this, there is a universally recognized marking, according to which each sign, symbol on the side surface of the tire corresponds to a predetermined value, which determines the area of its use.
The entire tire marking system , although quite understandable and simple, is not the subject of this article, but individual points will be considered in more detail and thoroughly. In particular, the tire load index characterizes the load capacity of the product, i.e., the weight that it can withstand. This index is located on the side of the tire after size (for example, 170 / 60R16) and is a two-digit number.
Each value that has a tire load index corresponds to a specific load that the product can withstand. The higher the index value, the greater the load the wheel can withstand. So, the indicator 82 corresponds to a load of 475 kg, and the index 100 corresponds to a load of 800 kg. There are special tables in which the corresponding values are given: tire load index (as the tire load index is called in another way) and the maximum allowable load in kilograms.
It would seem that everything is simple. We take the value of the allowable load by the index, multiply it by 4 and get the weight of the car with the load that this tire can withstand, or rather, the allowable weight for such tires. But this is wrong, you can’t do that. The fact is that the tables show the maximum permissible load values to which the tire load index corresponds. And if you calculate the allowable load according to the above method, you get the maximum value of the allowable load. And no product can be operated under extreme conditions. Therefore, with such an estimate, it is necessary to reduce the permissible load by 20% when using tires on a passenger car, and by 30% when using on an SUV.
This is not all the restrictions on determining the allowable load on the bus. There is such a thing - "weight distribution" of the car. It implies how the load is distributed along the axes of the car. For example, 30% of the loaded car load falls on the front axle, 70% on the rear axle. It is quite difficult to take into account the weight distribution; such data are usually not published.
And another factor to consider is the higher the tire load index, the thicker the product and the greater its safety margin. And this means that the elasticity of such a tire is less, and the possibility of depreciation, compensation of road roughness is worse. All bumps and bumps from bumps, pits and bumps will be transmitted more to the car body, which will make the trip less comfortable and cause additional wear on the suspension.
Another equally important parameter that you need to use when choosing a tire is the speed index. It is applied near the load index and is usually indicated by a Latin letter. As an example: J means that it is allowed to use this tire at speeds of up to 100 km / h, and the designation P means use at speeds of one hundred and sixty km / h. Two-letter symbols usually refer to tires rated for speeds greater than two hundred km / h. Needless to say, the speed of the car should not even come close to the permissible value set for this type of tire.
These two indicators in the marking, tire speed and load index, allow you to evaluate the possibility of using this product on a car, taking into account your individual needs and driving techniques. And it is best to be guided by the passport of the car, in which the manufacturer indicates the types of tires that are acceptable for use.