The goal is to better understand the strip shape and hardness variability issues that appear after hot rolling on two distinct high strength steel grades A and B. These issues strongly affect the yield loss of the two grades and are mainly due to late austenite transformation in the coil during its heterogeneous cooling in the coil yard after mandrel removal. To tackle these problems, an existing thermo-mechanical coil cooling model is calibrated on the two grades using industrial temperature measurements of the coils taken with infrared cameras (to tune the coil cooling temperature model) and using laboratory dilatometric tests to tune the phase transformation kinetics model of each grade. The infrared cameras reveal a difference of cooling kinetics between the two grades attributed to a difference of phase transformation kinetics: one grade is mainly coil transforming (grade A) while the other is rather run out table transforming (grade B). This difference was confirmed by the TTT and CCT diagrams established on the two grades with the laboratory dilatometric tests. Furthermore, the calibrated coil cooling model clearly shows that the slow kinetics of coil cooling after mandrel removal depends not only on material parameters, boundary conditions, coil geometry and phase transformation kinetics but also on the heterogeneous contact pressure between laps in the radial direction of the coil. Once calibrated, the model is used to compare the two grades and analyse several new rolling practices to mitigate the issues. Finally the industrial evaluations of some of these new practices are presented together with the yield benefits.