Winter is coming :) Tire size for gen3?

Hello everyone, another topic from me

This will be my first winter with the Prius and I have to get winter tires soon. I prefer to have two dedicated sets of wheels with tires and just remove the summer and put the winter or vice-versa without visiting the tire shop. Mine has the 17" wheels but I'm thinking of smaller size for the winter.

Around here finding a good set of wheels with PCD 5x100 is very (VERY!) difficult, believe me... Prius is not a common car and I have to find wheels from other Toyota models. I've found that the first gen Avensis (don't know if you have it in the US?), Corolla and Celica have 5x100 PCD. Avensis is very popular model here, but since only the oldest ones have 5x100, the most common wheels are steel 15".

I tried the 15" steel wheels on the hubs, they fit fine and rotate freely without touching the brake calipers. Their offset is 39 (6J), so their outside ends will be almost where the 17" alloys (offset 50, 7J) are.

I'm looking for your advice, do you think the Prius will feel fine with 195/65/15 in the winter/snow/ice? Or maybe 205/55/16 will be a better choice?

The Prius is not a light car and maybe the wider tires will go better trough the snow, but the 16" set costs twice the 15" and can't decide if it's worth it.