While the whole of the development of the global automotive industry has been driven by the need to reduce exhaust emissions, vehicle emissions analysis experts Emission Analytics’, have produced new data to say the biggest threat may not now be from the tail pipe but from tyres.

Tyres contain thousands of chemicals derived from crude oil, many of them volatile organic compounds. Emissions Analytics’ estimates suggest that around 300,000 tonnes of ‘rubber’ are released every year from passenger cars in Europe and US alone, the equivalent of over forty million brand new, entire tyres. These particles go into the air, soil and watercourses. Added to this, the tyre labelling scheme in the EU, only rates rolling resistance, wet grip and noise and has no ratings on environmental performance.  

Emissions Analytics’ says “While we have been occupied with reducing exhaust emissions to control air quality problems, other sources of pollutants have not received the same attention historically.  Now that tailpipe emissions of modern internal combustion engines generally well below regulated limits for pollutants, focus is now turning to ‘non-exhaust emissions’, which cover tyres.  Emissions Analytics’ testing shows that, in normal driving, tyre wear emissions are about one hundred times greater than tailpipe particle mass on a modern ICE vehicle.”

Other non-exhaust emissions such as particles from brake and road wear, as well as re-suspended solids, are also a concern. Tyre wear emissions are also likely to grow as vehicles continue the long-term trend of becoming heavier, especially in regard to SUVs.

Characterising tyre wear emissions requires measuring both the wear rates and chemical make-up of the particles.  This enables a quantification of the amount of individual chemicals that are released into the environment.  This information can then be put together with toxicity ratings to assess the potential effect on human health, wildlife and biodiversity

Emissions Analytics recently tested a range of different tyres and concluded that the average vehicle travelling 16,000km per year would shed 0.5kg per year on average over its lifetime.  As there are almost 600 million vehicles in Europe and the US, this is equivalent to 300,000 tonnes of particles.  An average tyre weights around 8kg, hence the total amount shed is equivalent to almost 40 million whole tyres. These figures do not include tyre wear from heavy-duty vehicles, which would also be significant.

In its test Emission Analytics’ also found that tyre make up varies significantly and the choice of tyre can have a major impact on the dangers they create. Therefore, choices of tyre when the car is first sold and at subsequent tyre changes, are directly relevant to the vehicle’s environmental impact, and requires deeper and urgent study.