The rolling resistance of tyres may differ greatly. A nearly 40% difference in rolling resistance transforms into an approximately 6% difference in fuel consumption. Thus, the tyre can save both the environment and money. With the current fuel prices, a tyre with a more economic rolling resistance can save nearly 300 euros over a driving distance of 40,000 kilometres. A wise choice of tyres and a careful driving style also help to significantly reduce the CO2 emissions generated while driving.
Rolling resistance refers to the energy consumed in the deformation that takes place when the tyre grips the road. This deformation, and the amount of energy it requires, can be regulated with structural and material choices in tyre design. Examples of factors that increase energy consumption include the tyre temperature, tyre pressure, load index and tyre wear, as well as air resistance and turbulence depending on the driving speed. Furthermore, a 0.5-millimetre water layer may increase rolling resistance by 50%.
Rolling resistance affects the environment throughout the tyre’s useful life. Light rolling corresponds to lower fuel consumption and CO2 emissions. Rolling resistance is measured in terms of a rolling resistance coefficient: the greater the coefficient, the heavier the tyre rolls. The average rolling resistance value for contemporary tyres varies from 1 to 1.2.
Only about 20–30% of the energy contained in fuel can be used to move a vehicle. This energy is used to accelerate and brake, but also to overcome rolling resistance and air resistance.