Ricardo releases new report on brake and tire wear emissions
9 December 2025
A newly published report by Ricardo for the UK Department of Transport (DfT) provides new insights into the nature non-exhaust particle emissions. Following the Phase 1 study, completed in 2023, the Phase 2 Final Report focuses on measuring real vehicle emissions from brake and tire wear from vehicles with different types of powertrains.
This latest research dives deeper into the variables influencing non-exhaust particulate emissions, the role of regenerative braking, and the effectiveness of reduction technologies—critical insights as Euro 7 will introduce limits for brake and tire wear.
Key highlights of the report include:
- Brake & Tire vs Exhaust Emissions: Non-exhaust emissions from brakes and tires are now a major source of road traffic particles as exhaust emissions fall
- Brake Pad Choice Matters: Low-dust and ceramic brake pads produce the lowest fine particle emissions (PM2.5), while higher pad cost does not guarantee lower emissions
- Regenerative Braking Is Positive: Electric and hybrid vehicles with regenerative braking significantly reduce brake-related PM2.5 emissions compared to petrol and diesel cars of the same weight
- More Weight, More Emissions: The extra weight of EV batteries increases brake emissions slightly, but regenerative braking more than offsets this effect for PM2.5
- Nanoparticles Harder To Reduce Than PM: Regenerative braking has little impact on nanoparticle numbers (PN10), which remained similar across ICE, PHEV and EV vehicle types
- Tire Emissions Are Mostly Volatile: Tire wear emissions are dominated by volatile particles; solid PM2.5 from tires is very low and often barely detectable
- Tire Size And Age Effects Hard To Determine: Larger tires lose more mass, but size, age, and brand had no consistent effect on PM2.5 or PN emissions
- Braking Style Matters: Hard, high-speed braking can increase brake PN emissions by up to 100 times compared to gentle braking
- Reduction Devices Show Promise: A brake dust capture system cut PM2.5 by over 40%, while a tire device captured large particles but not PM2.5
- Policy Implications Arise: The findings support introducing limits for brake and tire particle emissions, highlight the need for further research and continued innovation in non-exhaust emission controls and support evidence-based policy and innovation for cleaner air and healthier communities