If it came off the rim then it was possibly underinflated, or the wrong tyre for the wheel
Most tyre fitters will have a look at the rim where the tyre sits, and will wire brush away any possible corrision, they are fitting the tyre and they have to be responsible for what they are fitting the tyre to. IMO
I have used Nankangs on the back now for over a year, offer more grip than the pirelli's on the front do, especially in the wet where IMO the Pirellis are very poor. The whole carcass of the Nankang seems good quality to me, never had any problems with them.
I wouldnt mind two more, does anyone know of the Nankang dealer where I can get them direct?