- There is a 13-30% reduction in tire roadwear particles (TRWP) for every 10 km/hr speed reduction
- 5.9 million tonnes of tire roadwear particle emissions are generated globally
One of the biggest challenges facing tire manufacturers is the sustainability issue of tire roadwear particles (TRWP), a subset of microplastics. There are currently no regulations regarding TRWP, but Euro 7 will have new standards that will regulate TRWP based on the weight generated per kilometre per ton of load. This report examines the relationship between the size of the TRWP, the particle size distribution and tire materials, tire construction, road conditions, road type and other considerations.
With rising pressure to minimise tire particulate emissions, this expert study examines the technical and regulatory challenges facing tire makers and the steps they are taking to combat TRWP. In particular, it explores the long-term impacts of new tire wear testing obligations contained in the Euro 7 standard, and US legislation restricting 6PPD. Smithers analysis explores the tire material sets and construction innovations that can be used to improve tread durability, while maintaining performance and managing the transition to more sustainable transportation.
Key questions
- What steps are tire manufacturers taking to improve wear and reduce the environmental burden of TRWP?
- What role do automakers and government play in developing an overall solution?
- What are the technical challenges of mitigating tire wear particles under proposed regulations?
- What are the key opportunities in sustainable transportation?
This report benefits
- Tire makers and producers of tire materials
- Equipment suppliers to the tire industry
- Participants in the tire markets value chain
About the author
Howard Colvin has many years of experience in the tire industry with 22 years at Goodyear and 12 years with Cooper. At Cooper he worked in the Advanced Technology group and led Cooper’s consortium of academia, industry and government to develop a guayule concept tire. Howard is the 2021 Melvin Mooney Distinguished Technology award winner for exhibiting exceptional technical competency in rubber science and technology.
Executive Summary
- Size of the problem
- Key drivers for regulating TRWP
- Data gaps
- Key issues and challenges to address
- Suggestions on approaching the problem – Prevention to mitigation
Introduction and methodology
- Report scope
- Report objective
- Methodology
- List of definitions
- Abbreviations and glossary of terms
Introduction to tire wear particles and the regulatory landscape
- Size of the problem
- TRWP as a microplastic
- Mechanisms of tire wear and effect on TRWP
- Size distribution of TRWP
- Effect of non-tire variables on the generation of TRWP
- Pavement
- Driver behavior
- Vehicle speed
- Vehicle load
- Ambient temperature and humidity
- Traffic patterns
- Relationship between 6PPD and TRWP
- Health effects of TRWP
- Plant/animal
- Human
Technical challenges of mitigating tire wear particles under Euro 7 and US regulations
- Proposed regulations TRWP
- Proposed regulations 6PPD
- Data gaps
- Testing issues for TRWP
- Distinguishing TRWP from other materials
- Markers for TRWP
- Testing protocols
- Substituting for environmentally
- Unfriendly materials
Impact of materials on tire wear particles
- Fillers
- Elastomers
- Antioxidants and antiozonants
- Curatives
- Plasticizers (both resins and process oils)
- Substitution of more environmentally friendly materials to reduce toxicity of TRWP
The influence of tire design and vehicle type of reducing tire wear particles
- Effect of studded tires
- Effect of tread pattern on wear
- TPMS and self-inflating tires
- New generation wide based tires
- Effect of EVs on tire wear
- Effect of self-driving vehicles on tire wear
- Modelling of tire wear
Opportunities for more sustainable transportation
- Importance of Life Cyle Analysis to the question of sustainability
- Techniques for the management/mitigation of TRWP
- Importance of the involvement of the tire industry, government and academia to sustainable transportation
- Example of a regulatory action in progress – 6PPD and its relationship to TRWP
- Suggestions on how the tire industry, government and academia can work together more productively
- Potential for future regulations
- Ongoing work by the tire industry in sustainable transportation
Tables
- Classes of chemicals found in TRWP or TRWP leachate
- TRWP contributions to microplastics by country
- Reported LC50 of 6PPDQ to various salmonoid species
- Relationship between vehicle speed and generation of TRWP
- Comparison of Tire-Roadwear Particles, Tire Wear Particles, and Road Particles
- Contribution of TRWP to microplastics by country
- TRWP emission factors for different experimental conditions
- Markers for TRWP
- Chemicals found in TRWP or TRWP leachate
- Potential substitutes for environmentally unfriendly materials
- Comparison of truck tire wear – Silpara SMC vs conventional truck tread
- Effect of silica level on TRWP generation
- Effect of silica level on TRWP size
- Use of hydrocarbon resins to improve wear – Formula
- Use of hydrocarbon resins to improve wear – Results
- Glass transition temperatures of process oils
- Use of E2C to improve wear
- Effect of tire type on TRWP
- Impact categories for LCAs
- Overall conclusions from tire LCA to 2021
Figures
- 6PPD and 6PPDQ in the environment
- Formation of 6PPDQ from 6PPD
- Major transformation products from 6PPD
- Non-exhaust emissions of PM2.5 and PM10 for EU28 countries
- Publication of articles on TRWP since 2002
- Management options for TRWP
- Structure of Silpara SMC
- Formation of aniline from DPG
- Growth in the EV market
- Steps in a LCA analysis
- Life cycle of a tire
- Management options for TRWP
