On the left, characteristic velocity in the shoulder for every runs (crosses) for all vehicle speeds for new (up) and worn (down) tires (blue V₀ = 30 km/h, orange V₀ = 40 km/h, yellow V₀ = 50 km/h, violet V₀ = 60 km/h, green V₀ = 70 km/h and red V₀ = 80 km/h). The dashed lines represent the mean value deduced from all runs. On the right solid line is the ensemble averaged value obtained from the left values. Dashed line is the quantity . Solid lines are linear regressions for both cases (up and down). Error bars are associated errors deduced from the used runs (left).