I drive a 2023 GMC Terrain SLE w/ Elevation pkg. Stock my tires are 235/50/R19 with 7.5" wheels.

Wondering what size tires (width, aspect ratio) I can downsize to for winter to save some $. I will likely go with 18 if I can… is going down 2 inches in rim inadvisable? Lastly, what wheel width should I go with for the downsized tire?