You would use 195/65/15 in place of 205/55/16. The question is whether the 15" wheel will clear the brakes. If the base model of the car comes with 15" wheels and you don't have any brake upgrades as part of the GT package, you should be fine. Otherwise, you probably have to get 16" rims + tires for winter.
Tiretrends has a selection feature that will give you your options. For that car I think you would want to get something like a Toyo Garit HT, Pirelli 210, Hankook 300, etc, basically an H-rated tire that will match the handling characteristics.