ETRTO proposed three ways to estimate service life (TA-36-04): tread depth measurements, initial tread depth and abrasion index, and tread mass. JRC presented a service life index (TA-32-04) based on tread depth measurements and conducted a preliminary assessment of the second concept. Service life is estimated by linear extrapolation to 1.6 mm from tread measurements at test start and end. The Service life index is calculated as the ratio of candidate to reference tyre service life. Next steps include confirming the equation for service life via tyre characteristics and clarifying which tyre characteristics are needed.