I've got an '05 S cabrio with sport package and an aero kit. This is my daily driver. I'm currently running almost dead OEM 205/45/17 Dunlap Sport 9000 DSST tires. I'm leaning towards getting non-runflats.

I'm also looking at picking up a set of cheap rims and putting snow tires on them. My question is can I use 16 inch rims for the snow tires or will that cause me to become the worlds smallest snowplow?

My suspension is not adjusted from factory settings.

 

sure you can. 195/55/16 or 205/50/16.

narrower is better for snows.

 

Yes, 16" stock rims would work. 16x6.5
or
aftermarket 16x7 rims.

Check with tirerack.com for winter wheels