Tire size designation, load-bearing capacity and speed rating

WARNING
Exceeding the stated tire load-bearing capacity and the approved maximum speed could lead to tire damage or the tire bursting.

Therefore, only use tire types and sizes approved for your vehicle model. Observe the tire load rating and speed rating required for your vehicle.

1 Tire width
2 Height-width ratio in percentage 3 Tire code
4 Rim diameter
5 Load bearing index
6 Speed rating

General

: depending on the manufacturer's standards, a letter is imprinted into the tire wall before the size description.

If there is no letter preceding the size description (as shown above): these are passenger vehicle tires according to European manufacturing standards.

If "P" precedes the size description: passenger vehicle tires according to U.S.

manufacturing standards.

If "P" precedes the size description: light truck tires according to U.S. manufacturing standards.

If "T" precedes the size description: these are compact emergency spare wheels at high tire pressure, to be used only temporarily in an emergency.

Tire

width

: tire width 1 shows the nominal tire width in millimeters.

Height

-width

ratio

: height-width ratio 2 is the ratio between tire height and tire width.

The aspect ratio is calculated by dividing the tire width by the tire height. The resulting quotient is given as a percentage.

Tire

code

: tire code 3 shows the tire type.

"R" represents radial tires; "D" represents diagonal tires; "B" represents diagonal radial tires.

Optionally, tires with a maximum speed of over 149 mph (240 km/h) may have "ZR" in the size description, depending on the manufacturer (e.g. 245/40 ZR 18).

Rim

diameter

: rim diameter 4 is the diameter of the bead seat, not the diameter of the rim flange. The rim diameter is specified in inches (in).

Load

bearing

index

: 6 load bearing index 5 (also load index) is a numerical code that specifies the maximum load-bearing capacity of a tire.

Do not overload the tires by exceeding the specified load limit. The maximum permissible load can be found on the vehicle's Tire and Loading Information placard on the B-pillar on the driver's side .

Example: Load-bearing index 91 indicates a maximum load of 1356 lbs (615 kg) that the tires can bear. For further information on the maximum tire load in kilograms and pounds, see .

For further information on the load bearing index, see "Load index" .

Speed

rating

: speed rating 6 specifies the approved maximum speed of the tire.

Tire data is vehicle-specific and may deviate from the data in the example.

Regardless of the speed rating, always observe the speed limits. Drive carefully and adapt your driving style to the traffic conditions.

Since 2009, tires in Europe which correspond to the noise limitations of Directive ECE-R 117 show an >>S<< (Sound) mark. This identification follows the type approval number and has no connection with the speed rating.

Summer tires

R Optionally, tires with a maximum speed of over 149 mph (240 km/h) may have "ZR" in the size description, depending on the manufacturer (e.g. 245/40 ZR18).

The service specification is made up of load-bearing index 5 and speed rating 6.

• If the size description of your tire includes "ZR" and there are no service specifications, ask the tire manufacturer in order to find out the maximum speed.

If a service specification is available, the maximum speed is limited according to the speed rating in the service specification.

Example: 245/40 ZR 18 97 Y. In this example, "97 Y" is the service specification.

The letter "Y" represents the speed rating and the maximum speed of the tire is limited to 186 mph(300 km/h).

• The size description for all tires with maximum speeds of over 186 mph (300 km/h) must include "ZR" and the service specification must be given in parentheses. Example:
275/40 ZR 18 (99 Y). The speed rating "(Y)" indicates that the maximum speed of the tire is over 186 mph (300 km/h). Ask the tire manufacturer about the maximum speed.

All-weather tires and winter tires

Not all tires with the M+S marking provide the driving characteristics of winter tires.

In addition to the M+S marking, winter tires also have the snowflake symbol on
the tire wall. Tires with this marking fulfill the requirements of the Rubber Manufacturers Association (RMA) and the Rubber Association of Canada (RAC).

These tires have been developed specifically for driving on snow.

When the electronic speed limiter is set, your vehicle is prevented from exceeding 130 mph (210 km/h).

The speed rating of tires mounted at the factory may be higher than the maximum speed that the electronic speed limiter permits.

Make sure that your tires have the required speed rating, e.g. when buying new tires. The required speed rating for your vehicle can be found in the "Tires" section .

Further information about reading tire data can be obtained from any qualified specialist workshop.