Why do tires produce particles?
Tires are one of the most important safety components of a car. In addition to supporting the vehicle’s weight, absorbing impacts and withstanding multiple weather conditions, tires are a car’s only connection to the road. This is why the grip between a tire and the road surface is essential to tire safety and performance, and this critical grip also leads to abrasion of both tire and road surface, producing tiny debris called tire and road wear particles (TRWP). TRWP are a mixture of tire tread and road pavement material.
Understanding the impact of TRWP
USTMA and its member companies are committed to understanding any potential impacts of tire and road wear particles. Since 2005, our members have supported peer-reviewed scientific studies related to TRWP conducted by the Tire Industry Project (TIP) organized under the World Business Council for Sustainable Development (WBCSD). TIP has assessed potential environmental and human health impacts associated with particles from tires and more information can be located on the organization’s website.
USTMA supports additional research on TRWP that considers the latest science and most comprehensive methodologies, such as those developed by TIP, to gain a deeper understanding of any potential human health or environmental risks associated with TRWP. Read more about the industry's commitment to understanding and mitigating TRWP here.
Can TRWP generation be reduced?
Many factors impact tire wear, including tire design, vehicle characteristics (such as weight, distribution of load, location of driving wheels and suspension types), road surface (material, runoff design, roughness), weather (humid or dry, hot or cold), road topology (hilly or flat, winding or straight), and driving behavior (aggressive or smooth driving, high or moderate speed, respecting the correct inflation pressure, braking). As a result, there is no one-size-fits-all solution to reduce tire wear and the generation of TRWP.
Effective reduction of TRWP will require a multi-faceted approach. Strategies to reduce the generation of particles from tires could include:
Innovations in tire technology
New developments in the automotive and infrastructure value chains (such as devices that collect particles and smoother pavement surfaces made with rubber modified asphalt)
Ensuring proper tire inflation and smooth driving behavior
Innovation driving change
One of USTMA’s sustainability visions is to improve driving performance of the tires we design, make and sell. For example, USTMA members are increasing the use of advanced compounds in tire tread which helps to improve vehicle fuel efficiency leading to fuel savings, reduced vehicle CO2 emissions, and better tire wear performance (e.g., Terrance E. Hogan, “Functional Polymers Improve Tire Performance,” Rubber World ).
In addition, incorporating sustainable infrastructure in roadway development can provide long-term solutions for reducing TRWP. Specifically, USTMA is encouraged by the documented benefits of rubber-modified asphalt (RMA). A 2006 study, conducted by the Arizona Department of Transportation found that rubber-modified asphalt can reduce tire wear by up to 50 percent.
Green infrastructure, such as stormwater infiltration galleries and bioswales (rain gardens), has also proven effective in reducing the impact of potential pollutants:
The San Francisco Estuary Institute (SFEI) found that microparticles were well captured by raingardens, reducing microplastics in stormwater runoff by 91 percent.
The U.S. Environmental Protection Agency identifies the use of bioswales as a solution for reducing pollutant loads in stormwater.
CalRecycle research found that stormwater infiltration galleries made with tire-derived aggregate reduce stormwater pollutants such as zinc and iron by over 80 percent.
Research by the University of Minnesota found stormwater galleries with tire chips reduce pollutants in stormwater runoff by over 60 percent.
Rebuilding America’s roads can be done with the future in mind, including investments in technologies that increase driver safety and reduce environmental impacts such as roadway runoff. USTMA, therefore, supports additional scientific research into the use of sustainable infrastructure technologies to better understand their long-term benefits, performance, and environmental impacts.
How consumers can make a difference
Drivers can reduce the amount of TRWP produced by maintaining proper tire pressure, since under-inflated tires can impact tire safety, performance and tread life by accelerating tire wear. Drivers can also reduce the amount of TRWP produced by driving smoothly, as aggressive driving accelerates tire wear. USTMA recommends that consumers check their pressure at least monthly to ensure proper inflation and to maximize the performance and life of the tire.
More on TRWP mitigation
To learn more about mitigation options for TRWP, see Section 3.3 of the OECD Policies to reduce microplastics pollution in water: Focus on textiles and tyres and the ETRMA Way Forward Report.