Tire development and the reconciliation of demands for environmental performance and driving safety

Rolling resistance is the resistance that occurs due to deformation of the rubber and to friction when a tire rolls on the road. This resistance has a direct impact on a car’s fuel consumption and on CO₂ emissions.

• The rule of thumb is that approximately 20% of a car's fuel consumption is attributable to its tires.

Therefore, the reduction of rolling resistance is a direct measure to lower CO₂ emissions.

• The rule of thumb is that 10% less rolling resistance is equal to a 40 kg reduction of CO₂  emissions per car per annum.
  (based on a medium-size car traveling 20,000 km a year)

And yet a high-tech tire must be as balanced as possible in all of its characteristics. If one focuses entirely on improving just one characteristic during tire development, other product characteristics automatically suffer as a result of the interrelated physical processes. There are about 70 conflicting goals in the development of tires. But one of the key conflicts is:

A 10% reduction of rolling resistance causes a 10% deterioration in the tire’s wet braking performance. Braking distance is also much longer.

• The rule of thumb is that 10% less rolling resistance is equal to an 8 m longer braking distance*, which is equal to an impact speed of 35 km/h.
  *(ABS braking on a wet road, from 100 km/h to a standstill).

We assign top priority to safety. So a short braking distance, good handling and superb wet-weather performance must not be neglected in order to reduce the rolling resistance. Thanks to technical innovations (e.g. the use of new rubber compounding technologies, modifications to tire design and the incorporation of new materials) we have succeeded in lowering the rolling resistance of Continental tires by about one-third in the past ten years while significantly improving safety-critical features. Thus softening one of the major conflicts in tire development. Realistically speaking though, it will only be possible to almost halve the rolling resistance within a time frame of the next 30 years.