Not only the dimension: what else can be read from the inscriptions on the tires
Well, now is the time to start buying a new set of tires. Of course, you will get a final opinion on the chosen model only after you have driven several thousand kilometers. Perhaps everything will be fine with you, or perhaps some aspects will disappoint you … However, a lot of useful information could also be obtained in a tire store. It was enough to read the inscriptions on the side.
Unfortunately, most of us just read the name of the manufacturer, the name of the model and, of course, the size. And if you should not expect problems with determining the tire by manufacturer and model, in fact, the size is not so simple …
As a rule, the size is indicated by three digits in the format XXX / XX R XX. The first three digits are the profile width in millimeters. Profile, not a step! And if you put a tape measure on the tire, the tread width, as a rule, will be less than the specified three-digit number. The second two-digit number is the height of the profile, but not its absolute value, but the ratio between the height of the profile and its width, expressed as a percentage. However, off-road enthusiasts are well aware that the mud tires they respect so much have, as a rule, a completely different designation. In this case, the first number is the overall diameter of the tire in inches and the second number is the profile width, also in inches, such as 33 / 12.5 or 31 / 10.5. After all, it is extremely important for them that the tire has sufficient width: the wider the width and outer diameter, the greater the contact surface area, the less pressure on the ground and the greater the ability to roll on it is an obstacle. But at the same time, the tire still has to adapt to the wheel arches, even with technical upgrades in the form of a lift…
This is followed by the letter R. Contrary to popular belief, this does not mean the word “spoke" at all, but the fact that the tire has a radial structure (which does not negate the fact that the word RADIAL will be visible on the other part of the sidewall). By the way, initially all tires had a diagonal design, in which the cords of the inner carcass went from side to side diagonally. But in 1914, Hamilton and Sloper patented a tire design in which the ropes were sewn into the sides. This design turned out to be more difficult to manufacture and repair, but gave a number of advantages: the service life of such tires was increased, and the tendency to slip under side loads decreased, and the tension of the wires under load was lower, which made it possible to reduce the number of carcass layers. So, although it took almost 25 years to master the mass production of such tires, Almost all tires today are radial. However, for general development, we clarify that diagonal tires are still produced today, for example, for motorcycles, trucks and special equipment. In this case, instead of the letter R, the letter D or dash will appear in the measurement, and if the tire has a diagonal belt structure, the letter B will be in this position. Also, for greater clarity, the manufacturer can put a RADIAL or DIAGONAL inscription on the side.
The two numbers following the letter R indicate the DIAMETER of the tire rim in inches, so the common expression "tires with one or another spoke (for example, with 16 spokes)" is completely illiterate.
Not far from the size, the load and speed index is usually found – a two-digit number and a letter of the Latin alphabet. And here, to understand what the combination 92T or 99W means, you still have to look at the table (unless, of course, you have an eidetic memory or you have not graduated from the school of intelligence, where you were specially trained to memorize large numbers of information). The full table starts at zero (corresponding to a maximum load of 45 kg per wheel) and ends at 279 (13,600 kg per wheel), but we are interested in the range from 62 (265 kg) to 126 (1700 kg). / wheel) because this range accommodates every conceivable load that tires of cars, crossovers and SUVs can experience.
It is also worth considering that for a number of tires it is allowed to exceed the load by 10% of the nominal, but then after the index there should be letters XL, which can be replaced with the words EXTRALOAD or REINFORCED (" Reinforced") and manufacturers oriented to the American market may have an additional inscription MAX LOAD ("Maximum load") on the sidewall with two digits: the values of the maximum allowable load on the wheel in kilograms and pounds. Next to it, information about the maximum allowable or recommended pressure MAX PRESSURE in American designations (i.e. in PSI, pounds per square inch) or in more familiar SI units, such as kilopascals (kPa) may also be placed.
On the sidewalls of the tires, you can also see other inscriptions that speak about their design features. Therefore, tubeless tires are labeled Tubeless or TL, tires that require the installation of cameras – Tube Type, simply Tube or TT. The so-called "self-supporting" tires, capable of driving about 80 km after a puncture, are indicated by the inscription Run Flat or RFT.
There is another designation associated with the design characteristics of the tire: on the sidewalls of tires with a directional tread, the direction of rotation (Rotation) must be marked, and on tires with an asymmetric pattern, the outside (Outside or Side Facing Out) and (inner or side facing in) are marked .), and along the inner perimeter, at the very edge, the number of layers and the type of frame and waist cords are indicated. For example, the word "Steel" means that there is a metal cord in the tire structure.
But back to deciphering the load and speed index. The speed index table is a bit shorter:
After all, it is not even necessary to look at the letters in the Latin alphabet up to the letter J. Well, the above examples can be deciphered as follows: the first tire is designed for a load of up to 660 kg per wheel, when driving at speeds up to 190 km / h, the second – 775 kg at speeds up to 270 km / h. It should be clearly understood that the speed index W or Y does not mean that you can safely drive at a speed of 270 or 300 km / h even in a straight line, not to mention any maneuvers. This only indicates the ability of the tire to withstand the loads that occur at such speeds.
Next, consider the inscriptions indicating the purpose of a particular tire. The American marking standard clearly prescribes the marking on the surface of the sidewalls indicating the intended belonging of a particular product: tires for passenger cars must be marked P (Passenger), tires for light trucks are designated by the letters LTP o LT (Light Truck Personal and Light Truck respectively) and spare wheels – "conveyors" – must have the designation T (temporary).
The European label does not have such strict standards, but even here their purpose or performance may be indicated on the tires. For example, tires for SUVs and 4x4s are labeled "4×4", tires for commercial vehicles are labeled C, which stands for Cargo or Commercial. In this case, the prefix C is between the size indicator and the capacity index, for example 31×10.50R15 C 109R.
Letter designations indicating the purpose of a particular tire may also be included in the model name. So, the letters M / T (Mud Terrain) denote mud tires, A / T (All Terrain) – universal SUV, H / T (Highway Terrain) – highway, U / T (Urban Terrain) – urban, H / P (High Performance) – high speed, race. For example, the Toyo Open Country family has tires in all of these categories with the exception of H/P.
The next group of designations is related to seasonality. Tires can be winter, summer or all season. Winter tire markings include a snowflake pictogram and the word "winter". As for the signs M + S (Mud + Snow, "mud and snow"), then everything is not so simple. Most often, tires with the M + S brand are not purely winter, but all-season, in which case winter is understood more as “European” than “Scandinavian” or “Russian”. recently, winter tires are designated exclusively by a “snowflake”. But these tires can’t be considered off-road or mud tires either! As a rule, they do not have a bad enough tread, so on soft ground they instantly “wash out”, turning into a “slick”. Many off-road beginners have been disappointed to find that M+S tires are exactly what they need…
On the sides of the tires, which are not only, but also positioned as all-season tires, three pictograms are applied: with the image of snowflakes, clouds with drops of rain and sun. In addition, these tires may have additional markings on the sidewalls AW (All Weather), AGT (All Grip Traction) or AS (All Season").
Well, on the sidewalls of summer tires, you can apply additional markings in the form of an umbrella icon, as well as the inscriptions Aqua, Aquatred, Water, Aquacontact or Rain. These designations indicate that this tire model has a higher resistance to hydroplaning and can be considered a "rain" tire.
The country in which the tire was made is also important information. Note. This is the country where the plant where the tire was made is located, not the country where the manufacturer is registered. So, on tires with the names of world-famous Italian, French, German and Japanese brands on the sidewalls, you can find the inscription “Made recently”, tires of a Taiwanese brand can be produced in Vietnam or Thailand, and Toyo tires can be marked “Made by in Japan" and "Made in Malaysia.
For sale in the EU, tires must carry the CE certification mark with the European ECE product conformity number e11. However, for any car company, the most important market is the US, and tire manufacturers are no exception. Therefore, all tires around the world carry the DOT coding, developed at the turn of the century by the DOT Department of Transportation. This alphanumeric code contains a large amount of encrypted information, including the manufacturer’s trademark and the country in which the tire manufacturer is located, size, type and a number of other marked characteristics of the tire model. Some of this encrypted information duplicates other inscriptions on the tire map, but some data can only be found in this code. Alas, cracking this code is not at all easy, you need to know the “internal device” of the manufacturer or be able to use special applications.
Why is this so important, you ask, why tires are not vegetable or sausage … Alas, with a long violation of the conditions and rules of storage, tires regularly lose their quality. So after buying a brand new set of tires made 5-7 years ago and then stored in an unheated warehouse and not even in the recommended locations, you are likely to have balance problems and therefore wear very quickly.
And on the sides, you can enter a number of additional information, such as homologation codes. Approval means that a particular tire model has been approved by one of the car manufacturers for use in their vehicles. For example, code MO1 means these tires are for Mercedes cars, tires with codes N0-N3 are only recommended for Volkswagen Touareg and Porshe, code AO means these tires are approved by Audi, code means you have Toyota Auris tires and an asterisk (*) indicates that these tires are recommended for BMW vehicles.
In addition to the inscriptions on the side walls, there is another important source of information. Since 2012, all tires sold in Europe have received a special label that must be affixed to the running surface of the tyre. In addition to the article number, QR code and information about the manufacturer, tire model and tire size, this label contains information on a number of important parameters such as fuel efficiency and rolling resistance, external noise level and wet grip. All this information is presented in the form of clear pictograms and letters. For example, fuel efficiency is rated A to G. Tires labeled A will have the lowest rolling resistance coefficient (about 6.5) and the highest fuel efficiency, while tires labeled G will have a drag coefficient of 12. For identical vehicles equipped with these tires
The letters A to F and the wet grip coefficient are similarly classified. The worse the grip, the longer the braking distance, so that the difference in braking distance between a car traveling at 80 km/h and equipped with class A tires and class F tires is 18 meters.
Well, the level of acoustic comfort of a tire is indicated by a tire icon with schematic sound waves emanating from it. One wave indicates a quiet tire that is at least 3dB below the maximum permitted for Europe, two waves indicates a moderately noisy tire whose noise is within acceptable limits, and therefore such tires can be used in urban conditions. Finally, three waves indicate that the noise level of these tires is above the EU legal level and that they can only be used outside the EU.
And now, armed with all this information, you can safely start choosing a new set of shoes for your car.