Time evolution of the forward shock (red curves, labelled FS), reverse shock (orange curves, labelled RS), and outer boundary of the PWN (blue, pink, and green curves, labelled PWN). Time and radial position are given in characteristic units. Solid and dashed curves correspond to the output of numerical simulations for the three parameter set-ups presented in Table 1 (the solutions perfectly overlap for the forward and reverse shocks because SNR parameters are the same in all three cases). The dotted curves correspond to analytical expectations (see text).