  We discuss in this work the validity of the theoretical solution of the
nonlinear Couette flow for a granular impurity obtained in a recent work
[preprint arXiv:0802.0526], in the range of large inelasticity and shear rate.
We show there is a good agreement between the theoretical solution and Monte
Carlo simulation data, even under these extreme conditions. We also discuss an
extended theoretical solution that would work for large inelasticities in
ranges of shear rate $a$ not covered by our previous work (i.e., below the
threshold value $a_{th}$ for which uniform shear flow may be obtained) and
compare also with simulation data. Preliminary results in the simulations give
useful insight in order to obtain an exact and general solution of the
nonlinear Couette flow (both for $a\ge a_{th}$ and $a<a_{th}$).
