A wide range of tires for different brands of cars often greatly puzzles the car enthusiast and makes it difficult to choose. However, even experienced drivers cannot always purchase exactly the product that suits their car. Thus, almost every vehicle owner who has been using it for at least a couple of years knows what the radius or diameter of a tire is, its width, profile height and will be able to choose between winter, summer and all-season wheels. However, indicators such as mass or speed index are already familiar to a smaller number of consumers, although often these characteristics should be fundamental when purchasing.
Tire load index: table
The tire load index is a natural numerical indicator indicating a certain load that can be transferred to a given tire provided that the recommended pressure is inflated in it. This number is usually used solely for the driver to know the operating limits for his vehicle, but for safety reasons the manufacturer always provides a safety factor, meaning that the tire can physically bear this impact with an increasing factor of 1.3.
Marking on a car tire
In the automotive industry, there is the following table of the relationship between load indices and the actual permissible weight that can be applied to a given tire:
| Load Index | Tire load, kg | Load Index | Tire load, kg |
| 62 | 265 | 95 | 690 |
| 63 | 272 | 96 | 710 |
| 64 | 280 | 97 | 730 |
| 65 | 290 | 98 | 750 |
| 66 | 300 | 99 | 775 |
| 67 | 307 | 100 | 800 |
| 68 | 315 | 101 | 825 |
| 69 | 325 | 102 | 850 |
| 70 | 335 | 103 | 875 |
| 71 | 345 | 104 | 900 |
| 72 | 355 | 105 | 925 |
| 73 | 365 | 106 | 950 |
| 74 | 375 | 107 | 975 |
| 75 | 387 | 108 | 1000 |
| 76 | 400 | 109 | 1030 |
| 77 | 412 | 110 | 1060 |
| 78 | 425 | 111 | 1090 |
| 79 | 437 | 112 | 1120 |
| 80 | 450 | 113 | 1150 |
| 81 | 462 | 114 | 1180 |
| 82 | 475 | 115 | 1215 |
| 83 | 487 | 116 | 1250 |
| 84 | 500 | 117 | 1285 |
| 85 | 515 | 118 | 1320 |
| 86 | 530 | 119 | 1360 |
| 87 | 545 | 120 | 1400 |
| 88 | 560 | 121 | 1450 |
| 89 | 580 | 122 | 1500 |
| 90 | 600 | 123 | 1550 |
| 91 | 615 | 124 | 1600 |
| 92 | 630 | 125 | 1650 |
| 93 | 650 | 126 | 1700 |
| 94 | 670 |
Important!
All load index indicators are indicated on the very surface of the tires, and each consumer can easily, after reading this value, refer to the table provided and determine what maximum load the product he has chosen will withstand. To determine the approximate curb weight of his car, the buyer only needs to multiply the load indicator by 4. For example, if the index on the rubber surface is 93, which corresponds to a load of 650 kg, this means that the car can weigh 2.6 tons including cargo and passengers.
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Tire with load index 91
Tire load and speed index, explanation
In order to buy good car tires, it is not enough to know only their size and seasonality. Of course, this is basic information that the car owner must have; without it it is simply impossible to choose a tire. When choosing tires, some are guided by the brand name and to some extent this is correct. But if you take a tire from the best brand that fits the car and is appropriate for the season, then in this situation you can make a serious mistake, and its consequences can be the most tragic.
What does the marking hide?
Of course, the tread pattern and the cost of tires also largely determine our choice, but the load index and tire speed, the explanation of which will be presented below, play a much larger role. On the side surface of each wheel, even the most inexpensive one, there is a bunch of various information that is hidden in symbols and numbers; its importance should never be underestimated.
For example, from this encryption you can find out the following information:
- Tire model and tread type. This is very important information, since each tread type corresponds to a certain hardness of the rubber material. A tire of the same model, but with a different type of tread, may have different stiffness of the central and lateral parts of the contact area.
- The most famous inscription is the tire size, its seat diameter, height, width (height to width ratio).
- Tire production date.
- Designation of design type (radial or diagonal), tire type (tube, tubeless).
- Wheel rotation direction.
- Speed index.
- Load index.
The largest letters, of course, bear the manufacturer’s name and logo, which is what people pay attention to first.
Why know the load index?
In each country where tires are produced, the load index can be called differently, such as load index, maxload, load capacity index, but the meaning does not change. Moreover, the load is indicated not by a number, but by a letter, which most often misleads inexperienced motorists. Also, many people believe that this information is important mainly for truck tires, but this is completely wrong. This indicator plays a huge, if not even greater, role for passenger tires, motorcycles, mopeds, and here’s why.
Simply put, this is the maximum load on one wheel, at which the manufacturer guarantees the preservation of the characteristics of the rubber. The load is indicated in kilograms, and at the maximum permissible speed for the tire and if the optimal pressure is maintained. But what about working conditions, weather, lateral load, driving style, technical condition of the car, this will also affect the endurance of the rubber? Of course, that's the whole point.
Index tables and how to use them
Everything seems to be simple. Here is a table of tire load index (Table 1), here is a table of permissible speed load (Table 2). These values are exactly the same for all manufacturers and are standardized throughout the world. The letter (or number) indicates the index, and the table indicates the load value in kilograms. All that remains is to calculate the load on one wheel and buy tires that match the index.
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But the fact is that we can hardly calculate the exact load on the wheel. It is not enough to simply divide the mass of the car by four. Firstly, the load on the front and rear axles will be completely different, and secondly, a number of other conditions constantly intervene:
- surface temperature of the rubber material;
- instantaneous speed of the machine;
- how badly the wheel is worn;
- dependence of pressure on temperature.
And the list goes on. It is for this reason that the manufacturer gives a safety margin of 25-30%! And the driver should add the same amount when buying a wheel. However, in choosing a tire, the last word will always remain with the car manufacturer, who calculated the load capacity index not with a calculator in hand, but based on the results of lengthy tests.
Dependence of speed and load indices
The second table, presented just above, shows the maximum speed index. By analogy with the load index, the tire does not have a number, but a letter symbol. It seems that everything is simple here too - I looked at the letter, compared it with the data in the table, and bought tires. All that remains is not to exceed the permissible speed. Only here everything is not so smooth. Both indicators greatly influence not only the car’s handling and its load capacity, but also the comfort of movement in the cabin. After all, the harder the tire, the lower the speed index, and the softer the tire, the less load it can withstand.
Therefore, both indices are closely intertwined with each other, and this is not counting the roads on which we have to drive, and this fact again refers us to the car manufacturer. He tested the car, only he knows what maximum values the wheel should withstand.
Ideally, it would be good to start from the parameters of the tires that were installed on the car from birth, from the assembly line. However, no one bothers you to independently analyze the rate of tire wear and comfort in the cabin, handling and adequacy of prices. Therefore, the more we know about our tires, the more comfortable and safe it will be to use them. Good choice, velvet roads to everyone!
Decoding the load index for passenger cars
When purchasing new tires for his car, the buyer sees a line with markings on its side surface, for example, this 195/70/R15 89V, and he should know that 195 is the width of the sole with treads in mm, 70 is the height of the rubber profile, also in mm, R15 is the radius indicator in inches or diameter, V is the speed index, that is, what dynamic characteristics a car can have so that the tire does not wear out faster than the allotted time.
The number 89 in this line indicates the load index, which says, according to the same table above, that a weight of 580 kg can be applied to a given wheel, inflated to the maximum level, or the total curb weight of the car should be no more than 2.32 tons.
Knowing this value, the vehicle owner only needs to look at the table with the technical characteristics of his “iron horse” and select from there a similar load index value for his car. Smartphone owners can download the appropriate application to their devices, which contains all the initial data for each passenger car or truck, and, if necessary, determine exactly which tire they need.
Important!
Experts do not advise choosing a tire with a load index exceeding the value specified in the description, since a product that is too rigid has a profile that will hit the rim and suspension, and this will negatively affect the driver’s comfort in the car.
Tire with load index 140
Relationship between two indexes
In most cases, the logical fact is that the higher the speed index and its interpretation, the greater the load index that the car can withstand. It is worth noting that the speed indices indicated in the table from Q to T allow for a load that will take a limit value, both for the speed indicator and for the load itself. However, in the case of high-speed cars, a certain margin must be provided between the two indices.
When choosing tires if the emphasis is on speed, you need to pay attention to the following factors:
- manufacturer's recommendations;
- season;
- driving style.
Also, if it is not possible to purchase a tire, based on the manufacturers’ recommendations, it is best to give preference to those that have a fairly high speed rating.
What is Tire Load Capacity Index?
In addition to private passenger cars, which are usually intended for family or personal use, on Russian roads you can often find freight transport working for various enterprises.
So, these cars also have wheels and tires, and the owners have to change them, with the difference that the tire size for these cars is slightly different. The tire load index also differs from the same parameters for passenger cars, and it has the following features:
- This characteristic indicates the total load from the vehicle’s own weight and the maximum useful cargo weight that it can take on board. The tire load capacity index, the table given above, has its continuation for trucks, up to 279, or 136 tons per wheel, which is already used for special mining equipment.
- Unlike the load index for passenger vehicles, this indicator cannot be a two-digit number - 75, 88, 99, etc., but, taking into account the capacity of the body or van, it is immediately calculated for values from 140 and above.
- There are various calculators online for selecting tires for trucks depending on the maximum load that they can bear in accordance with the technical characteristics.
- So, for example, if a truck can be loaded according to the maximum permissible indicators from the factory up to 40 tons, and the car has only 2 axles, then its load index will be equivalent to 10 tons per wheel or, in numerical terms, the tire load index will be 188 .
- Also, unlike passenger vehicles, trucks often have dual wheels, and this means that their marking is written as 126/124, and means the ability of a single tire to withstand 1.7 tons, and a dual tire - 1.5 tons per wheel.
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Twin wheels on a truck
Another important indicator for a truck tire is the speed index, which indicates exactly the dynamic parameter at which the values indicated in the load capacity table can be transported at the speed calculated for the truck. So, for example, if the owner of a vehicle sees that the wheel intended for purchase is marked 178K, this means that the wheel can take on 7.5 tons, and the truck will safely reach speeds of up to 110 km/h.
In addition, these characteristics for heavy-duty commercial vehicles are E – 70 km/h, F – 80 km/h, G – 90 km/h, J – 100 km/h, L – 120 km/h, M – 130 km/h and N – 140 km/h.
Important!
For all the above load and speed indicators, numerous tire companies produce their products, and every owner of such a car will always be able to choose tires whose indices will completely coincide with the indicators listed above.
Decoding
The easiest way is to calculate the maximum load using the table we posted above.
Managers in car tire stores should also be savvy in deciphering indexes. Pay attention to the indexes recommended by the car manufacturer - they should be indicated in the car's operating instructions. The greater the difference in indexes between the tires you selected and those recommended by the manufacturer, the less comfort you will feel behind the wheel.
Tires for trucks are marked with two load indices. This is due to the fact that trucks often ride on dual wheels. And in this case, the double designation shows the load when using one or two wheels. There are no other differences in the tire load index between passenger cars and trucks.
What to look for when buying tires?
When choosing tires, you need to focus on two important parameters that are closely related to each other: speed and load. After all, it is the load that influences the nature of vehicle movement and determines the service life of automobile tires.
For example, with a small load, the noise level when moving the car will be minimal, but the tires themselves will wear out faster. If the load factor is high, the tires will be noisier but will last longer.
When purchasing tires for a passenger car, you need to focus on the speed at which you most often travel, and buy them with a margin of ten to fifteen percent more.
To avoid problems, for example, tire rupture while the vehicle is moving, you need to purchase products with a higher index. But here it is important not to overdo it. After all, if you decide to install tires with inflated parameters (for sports cars) on a passenger car, comfort while driving will suffer.
If the set includes tires with different speed limits, you need to install harder rubber on the front wheels. With this installation method, the wear on all four wheels will be approximately the same.
What are tire speed and load indexes and why are they needed?
One of the most important components affecting driving safety is the speed index. It determines the maximum permitted speed of the vehicle. Determined by three components:
- weight load;
- normal tire pressure;
- external weather or road environment - the quality of the road surface and weather conditions.
If all these parameters are within acceptable limits, then the speed specified by the manufacturer will allow you to operate the tire safely. This is a 100% guarantee from the manufacturer that the selected tire will not burst and will not lose all the most important properties.
The second important component is the index or, as it is also called, the coefficient of the maximum possible weight load. It shows the car owner how much weight can be put on a particular tire and make the car go very fast. The load index is expressed in kilograms and takes into account the total mass, that is, the weight of the car, driver and passengers. In another way, this parameter is called the load capacity index.
The marking of a car tire provides a load designation with a number from 0 to 279. To decipher it, you must use a special technical table. Full data is never used because most cars have a very narrow weight range. It is limited to indexes from 50 to 126. In terms of weight, this means from 190 to 1700 kg. These tires are used in passenger cars, crossovers and light trucks.
Speed and load indices on tire markings
Attention! Any tire can have two load indexes: normal and maximum permissible. The difference between them should be less than 10%. As a rule, there is an explanatory marking, for example, XL.
Example of tire marking: Michelin Energy 195/65/R15 91T, where:
- 91 - load index, allowing a tire weight of 615 kilograms;
- T - maximum permissible speed of 190 kilometers per hour;
