Emission of Inhalable Particles from Studded Tyre Wear of Road Pavements

Image of studded tyres.

Photo: Mats Gustafsson

In the following study, the particle generation from seven studded tyres was tested in the VTI road simulator. The results show that increased number of studs and increased stud force increase the emission of inhalable particles significantly.

New restrictions on the number of studs on studded tyres were introduced in Sweden and Finland in 2013. Regulations now allows 50 studs per meter rolling circumference. Alternatively, the tyres can be tested in a special wear test, the so-called over-run test, to be approved. This has resulted in studded tyres that follows the rule of the number of studs per rolling circumference meters, but also studded tyres that pass the over-run test, but have considerably more studs are present on the market.

The over-run test shall ensure that the tested tyre will not cause more road wear than a tyre with a maximum of 50 studs per meter rolling circumference. Since studded tyres are a major source of inhalable particles (PM10) in road and street environments, it is of interest to investigate the difference between the various studded tyre types also from particle emission point of view.

The results show that the tyre with the most studs (190) generates significantly higher PM10 levels than the other tyres while one of the tyres following the stud number regulations and have 96 studs results in significantly lower formation of inhalable particles than all other tyres tested. Increased number of studs increases PM10, PM2.5 and number concentration significantly, while increasing stud force significantly increases the concentration of PM10 and PM2.5. Temperatures in the tyre, pavement and air as well as relative humidity also have an effect on the particle levels.
The particle generation from seven studded tyres was tested in the VTI road simulator. The tyres have been tested at 50 kilometres/hour in a statistically optimal sequence during the four test days where various order of tyres used each day of testing.

VTI report 867A: Emission of inhalable particles from studded tyre wear of road pavements – a comparative study of studded tyres
Authors: Mats Gustafsson, Olle Eriksson
Link to full report in English

Mats Gustafsson Contact:
Mats Gustafsson
VTI, Sweden
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