[omasou]

Some things I have learned when switching between summer and winter tires on a performance car.

19" winters tire are harder to find than 18"

in snow, narrower tires perform better than a comparable wider tire, meaning if you can look for an 18" solution and consider narrower 18" if more than one will work

buy an extra set of rims if you can. Over the life of the tires you will spend more to unmount and mount tires + there are more opportunities for the installer to introduce an imperfection to the rims, this is an OCD concern.

use a square set up and buy a spare tire!! as Keith has already posted winter tires sell out and there is a high probability that you will not find a match in the middle of the season. Also the winter tires should last a few seasons which makes the probability of finding a match even lower in following years. This happened to me twice before I learned, e.g. damage to the sidewall