I am looking at getting a set of winter tire/wheel package from Tirerack : X-Ice Xi3 and MSW Type 85 (or 25). Tirerack order page shows centering rings. Does anyone know if they are plastic/nylon rings or aluminum rings ? Does the material matter ? I am worried about damaging the plastic rings when mouting/unmounting couple of times a year. Also, do their steel rims require centering rings - I cannot find the bore diameter of those wheels online. Anyone know ?
