Tire supporting Energy Transition

Climate change is a major issue of our time. Limiting the increase in global warming to 2°C by 2050 means reducing greenhouse gas emissions. The transport sector is responsible for around 26% of total energy-related CO ₂ emissions (6.7 gigatons of CO ₂ ). The European Commission has set itself the target of a 90% reduction in CO ₂ emissions from transport by 2050 (compared with 1990 levels), and has passed regulations to reduce CO ₂ emissions from new vehicles placed on the market in the coming years. Tires are affected by these regulations: in fact, tires with low rolling resistance demand less energy from the powertrain, thus reducing the energy consumption and CO ₂ emissions of vehicles on the road.

For any vehicle fitted with tires, each turn of the wheel causes the tire to deform to take on the shape of the ground. The tire develops an area of contact with the ground, through which all the forces required for acceleration, braking or cornering pass. By deforming, the tire also absorbs irregularities in the road surface. The tire's deformability is at the root of its rolling resistance. In fact, the rubber compounds that make up tires are viscoelastic materials. This viscoelasticity means that every time the tire rubber undergoes deformation, it dissipates energy in the form of heat. In the same way as other natural phenomena against which we have to fight to get around – wind, road gradient, vehicle inertia, etc. – rolling resistance contributes to vehicle fuel consumption. It is responsible for between 5 and 20% of the energy consumption of a passenger car, and between 15 and 40% of that of a heavy goods vehicle. . Lower rolling resistance is therefore synonymous with environmental protection and cost reduction.

The first part of this article presents the results of a tire life cycle analysis. It then looks at the mechanisms that generate rolling resistance, from the microscopic to the macroscopic scale. The final section looks at the regulatory aspects of rolling resistance and the link between rolling resistance and vehicle energy consumption.