Thanks for the tips, guys.
It being Labour Day weekend, I put the winter tires on the car. Summer's over!
Actually, I won't be using this car regularly until later in the fall.
As I mentioned, the winter tires are 2 sizes larger (65 vs. OEM 55 aspect ratio), and they really fill the wheel wells. Also, they're slightly offset to the outside more than the factory wheels (positive offset?). Net result: I think they're better aerodynamically. Well, they will be when there are smooth wheel discs on there (coroplast).
I'll snap a pic tomorrow.
Oh, and my butt-dyno says the ~6.5% taller gearing is better to drive, too.