The fuel efficiency category (scale from A to G) is determined on the basis of the rolling resistance coefficient. The wet grip category (scale from A to G) is determined on the basis of the wet grip index. And the external rolling noise category (three-tier scale) is determined on the basis of the limit levels specified in Annex II to Regulation (EC) 661/2009. The method for measuring the key data is specified in detail in Regulation 117 of the United Nations Economic Commission for Europe (UNECE).
- The method for determining the rolling resistance coefficient was defined on the basis of ISO Standard 28580. A practical test is carried out on a wet, smooth road surface to determine the wet grip index. Here, in a standardised vehicle the brakes are applied from an initial speed of between 87 and 83 km/h until the vehicle comes to a halt. The wet grip index is derived from the average deceleration of a test tyre between 80 and 20 km/h, divided by the average deceleration of a standard tyre. In order to ensure comparability, the regulation also specifies other parameters such as tyre pressure, condition and load, vehicle type, test surface, depth of water, etc. A slightly modified method is used for determining the wet grip index for tyres for trailers or for other special uses.
- The level of external rolling noise is measured in weighted decibels (Db[A]) with microphones alongside a moving vehicle. In this test, the vehicle rolls past the microphones in neutral gear and with the engine switched off on a dry road surface at a speed between 60 and 90 km/h. The microphones are positioned at a distance of 7.5 metres from the stretch of road, at a height of 1.2 metres. In order to ensure comparability, the regulation also specifies other parameters such as tyre pressure and condition, vehicle type, test surface, temperature, wind speed, etc. The definitive rolling noise level is based on an average of several measured levels adjusted by the temperature of the road surface.
The label provides buyers with information about the tyre's safety during braking on a wet road surface, as well as its rolling resistance and rolling noise level. These three criteria are essential indicators for choosing the right tyre.
For more detailed information, please refer to the TCS tyre test reports. These tests are carried out each year for selected winter and summer tyres.