Evolution of RSG simulation forward shock radius (upper panel) and shock velocity (lower panel) vs time up to the WTS. The profile is calculated along an exemplary diagonal ray from the origin in the [+x, −y, +z] direction. Predictions from the model of Truelove & McKee (1999) are also shown for the average and late cases as discussed in the main text. All velocities are in the centre-of-explosion frame.