MATERIALS DEVELOPMENT FOR LOWERING ROLLING RESISTANCE OF TIRES

Many countries are implementing regulatory programs to promote the use of transportation technologies that can reduce greenhouse gas emissions and enhance fuel economy of vehicles. These regulatory programs create a need for more durable and fuel-efficient tires. The increased cost of fuel for motor vehicles creates another driving force for improving the fuel economy of vehicles. Commercial vehicle operators recognize that fuel cost is a major driver of the total operating cost; therefore, they increasingly demand tires that are optimized for reducing the fuel cost of a trucking fleet. Rolling resistance of truck tires accounts for about one-third of the power required to move a heavy-duty truck and is the second most important contributor, after engine loss, to the total energy loss of heavy-duty trucks. Other than tire designs, rubber compound hysteresis contributes to the rolling resistance of tires, which affects vehicle fuel economy. There is a significant market demand, due to governmental regulations, concerns for the environment, and cost savings to the consumers, for developing tread compounds or tread compound systems that can reduce tire rolling resistance while maintaining the treadwear and durability of truck tires. This paper reviews materials technologies developed for reducing the hysteresis loss of rubber compounds at high temperatures, hence lowering the rolling resistance of tires. Compounding approaches that can be used to lower the hysteresis loss of rubber compounds and to reduce rolling resistance of tires also are discussed. Developments in elastomers and reinforcing materials, including nanoparticles, are highlighted, with focus on the benefits of those polymers and particles in reducing the hysteresis loss at high temperatures of rubber compounds.