Evening, just picked up a '18 premium wrx, I have a set of brand new 215/55r18 winter tires that I hope I can use in place of the stock 240/45r18 tires. Will there be any interference issues? They seem pretty close in size.
If you have the right wheels and the diameter is correct it will work.
Narrower tires are ideal for snowy conditions as the higher psi from the smaller contact patch push through the snow to the pavement giving traction. A wider tire will tend to float on the snow and slush causing more sliding