Test precision weighted analysis to exclude NOK data from the worn tyre wet performance test. Analysis of precision using dataset without NOK data shows the same trend as analysis based on full dataset. New coefficients for the GB formula significantly improve precision, which is now comparable to new tyre wet grip test. Strong correlation exists between current and new formulas, making it possible to continue current worn-tyre wet grip criteria. JATMA proposes to revise coefficients of the GB calculation formula based on Stage 1 data.