Tyre labelling: How is tyre performance compared?
The letters and colours shown on the tyre label indicate its performance level in terms of fuel efficiency, wet grip and external rolling noise. But what exactly does this mean? What does the grading scale correspond to? What is the difference between two classes?
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Energy efficiency: Indicates the tyre’s contribution to fuel consumption and CO2 emissions
The tyre label indicates its rolling resistance class. There is a significant difference between an A and a G class tyre.
• Fuel consumption: The difference between an A and a G class tyre represents 0.5 litres per 100 km, i.e 17.6 gallons of fuel per year (based on 10,000 miles / year).
• CO2 emissions: The difference between an A and a G class tyre represents 12 g /km i.e. 0.18 tonnes of CO2 per year. For info, a malus is applied to vehicles in the form of a carbon tax starting from 141 g/km of C02.
Fuel efficiency rating for passenger cars
|Rolling Resistance coefficient (RR), in kg/t (kilograms of resistance per tonne)||Labelling category|
|RR ≤ 6,5||A|
|6,6 ≤ RR ≤ 7,7||B|
|7,8 ≤ RR ≤ 9||C|
|9,1 ≤ RR ≤ 10,5||E|
|10,6 ≤ RR ≤ 12||F|
|RR ≥ 12,1||G|
Braking efficiency: The tyre’s wet grip performance
The class is determined by comparing the test results with those obtained with a reference tyre. Again, there is a significant difference between an A and an F class tyre (G class is not used).
• Braking: The difference between A and G class tyres represents a distance of 18 metres, i.e. the equivalent of 4 car lengths.
Wet grip rating for passenger cars
|Grip coefficient (G is the reference index)||Labelling category|
|1,55 ≤ G||A|
|1,40 ≤ G ≤ 1,54||B|
|1,25 ≤ G ≤ 1,39||C|
|1,10 ≤ G ≤ 1,24||E|
|G ≤ 1,09||F|
Noise efficiency: Tyre external rolling noise
• External noise: The performance difference between two noise classes is 3 dB, i.e. the noise level is increased or decreased by half.
1 black bar: Good performance. The level of tyre external rolling noise is 3 dB below the future limit.
2 black bars: Satisfactory performance. The level of tyre external rolling noise is in line with the future limit.
3 black bars: Poor performance. The level of tyre external rolling noise is above the limit set by the future standard but below the current maximum authorised limit.
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