Experimental investigation of tread wear and particle emission from tyres with different treadwear marking

The Treadwear Rating (TWR) provided on the sidewall of the tyre is a marking intended to inform the customer about the expected durability of the tyre. The current study explores whether there is a correlation between the TWR and tread mass loss, and especially between the TWR and tyre wear dust emitted in the form of PM10 and PM2.5. For that reason, two tyres of the same brand (B) but with different TWR and three tyres of different brands (B, C and D) but with the same TWR were tested at a constant speed of 70 km/h by means of the Swedish National Road and Transport Research Institute (VTI) road simulator. Tests performed on tyres with the same TWR but of different brands did not show statistically significant relations between TWR and measured tread mass loss or PM10, PM2.5 or PN concentration. This means that tyres with same TWR but of different brands have different behaviours in terms of material loss or PM and PN emissions under the test conditions used in this study. The test performed on the two tyres of the same brand but with different TWR showed instead a substantial (not statistical significant) difference in both total wear and PM10 emissions. The tyre with the higher TWR (B2) showed less wear and PM10 emissions compared to the B1 tyre having a lower TWR. Since only two tyres of the same brand and with different TWR were tested, this result cannot be generalized and more tests are necessary to confirm the correlation within the same brand. In general, the tyre tread mass loss showed no obvious statistical relation to PM10, PM2.5 or PN concentration. In all cases approximately 50% (by mass) of emitted PM10 fall within the size range of fine particles, while PN size distribution is dominated by ultrafine particles most often peaking at 20-30 nm.JRC.C.4-Sustainable Transpor