The base i3 comes with a square setup. That will fit on all i3's except possibly the i3S sport model (don't know, but expect they will work just fine) - just bolt them on.
FWIW, a narrower tire works better in the winter...wider ones tend to float on the deep snow rather than dig through it. The R3 is, I think a better tire than the Bridgestone. Don't know about longevity, but it shouldn't be an issue, either. Don't know of any wider winter tire that will fit the i3.