Designations on tyre sidewall
Note
Tyre dimensions
All tyres have a designation of dimensions, such as: 265/40 R21 98 W.
| 265 | Tyre width (mm). |
| 40 | Ratio between tyre wall height and tyre width (%). |
| R | Radial ply. The designation RF and symbol specify that the car is equipped with puncture-resistant tyres. |
| 21 | Rim diameter (inches). |
| 98 | Codes for the maximum permitted tyre load, Load Index. |
| W | Speed rating for maximum permitted speed, Speed Symbol. |
Wheel rim dimensions
All wheel rims have a designation of dimensions, such as: 8J x 19 x 50.
| 8 | Rim width (inches). |
| J | Rim flange profile. |
| 19 | Rim diameter (inches). |
| 50 | Offset in mm (distance from wheel centre to wheel contact surface against the hub). |
Weather condition classification
Here are some classification examples. Weather capabilities can also be defined with certain symbols.
| M+S or M/S | Mud and Snow. |
| AT | All Terrain. |
| AS | All Season. |
Tyre age
| DOT YLX2 0819 | Tyre Identification Number or TIN. This information helps the tyre manufacturer identify tyres in the event of safety recalls. |
- DOT1
- The first two characters are the code for the plant where the tyre was manufactured.
- The next two characters are the tyre's size code.
- The last four digits specify the week and year the tyre was manufactured. For example, 0819 means that the tyre was manufactured during week 08, year 2019.
Any numbers or letters shown in between are market codes chosen by the manufacturer.
Max load and pressure
| Max load 685 kg (1610 lbs). | Specifies the maximum load that the tyre can carry. |
| Max pressure 240 kPa (35 psi). | The maximum tyre pressure that the tyre should ever be subjected to. This limit is specified by the tyre manufacturer. |
Minimum permitted load index and speed rating
The tyre load index and speed rating might not be shown on the sidewall as this is not a legal requirement.
Type, materials and tyre rotation
| P | Indicates that the tyre is for passenger vehicles. |
| VOL | Volvo original tyres. |
| Plies: Tread 2 polyester, 2 steel, 1 polyamide. Sidewall 2 polyester. | States the number of cord layers or number of layers with rubber-coated fabric in the tyre's tread and sidewall. The tyre manufacturers must also state the layer materials used in the tyre and sidewall, which may be steel, nylon, polyester and certain other materials. |
| Arrow symbol | Tyres with a tread pattern designed to only turn in one direction have the direction of rotation marked with an arrow. |
Classification of uniform tyre quality
| Treadwear grade 200 | The treadwear grade is a comparative rating based on the wear-rate of the tyre in a standardised test. A higher value is better. |
| Traction grade AA | The traction grade is based on standardised straight-ahead braking traction tests. The traction grades, from highest to lowest, are AA, A, B and C. |
| Temperature grade A | The temperature grade reflects the thermal performance of a tyre that is properly inflated and not overloaded. The temperature grades, from highest to lowest, are A, B and C. |
From the Consumer Guide to Uniform Tyre Quality Grading
The purpose of this section is to aid the consumer in making an informed choice in the purchase of passenger car tyres.
All passenger car tyres must meet federal safety requirements apart from this classification.
Treadwear
The treadwear grade is a comparative rating based on the wear rate of the tyre when tested under controlled conditions on a specified government test course. For example, a tyre graded 150 would wear one and one-half (1 1/2) times as well on the government course as a tyre graded 100. The relative performance of tyres depends upon the actual conditions of their use, however, and may depart significantly from the norm due to variations in driving habits, service practices and differences in road characteristics and climate.
Traction
The traction grades, from highest to lowest, are AA, A, B, and C. Those grades represent the tyre's ability to stop on wet pavement as measured under controlled conditions on specified government test surfaces of asphalt and concrete. A tyre marked C may have poor traction performance. Warning: The traction grade assigned to this tyre is based on straight-ahead braking traction tests, and does not include acceleration, cornering, hydroplaning, or peak traction characteristics.
Temperature
The temperature grades are A (the highest), B, and C, representing the tyre's resistance to the generation of heat and its ability to dissipate heat when tested under controlled conditions on a specified indoor laboratory test wheel. Sustained high temperature can cause the material of the tyre to degenerate and reduce tyre life, and excessive temperature can lead to sudden tyre failure. The grade C corresponds to a level of performance which all passenger car tyres must meet under the Federal Motor Safety Standard No. 109. Grades B and A represent higher levels of performance on the laboratory test wheel than the minimum required by law. Warning: The temperature grade for this tyre is established for a tyre that is properly inflated and not overloaded. Excessive speed, underinflation, or excessive loading, either separately or in combination, can cause heat buildup and possible tyre failure.