A couple of years ago, I purchased a winter tire/wheel combo for my '04 coupe from Tire Rack. Blizzaks were not available at the time. If I remember correctly, they sold me 17" wheels (Sport edition).

Sadly, I wrecked my '04 last week. It was the first new car I ever bought for myself. It was twilight blue...

I replaced it with an '06. Athens/Graphite.
The new '06 has 19" wheels and rear active steer.

What problems, if any, will I encounter if I put the old winter tire set up on the new car?

 

Your old setup may or may not clear the calipers...some 17" do, some don't. I believe stock 06 rims are 18" btw. You might want to give tire rack a call to see if your sport editions will work. Otherwise you can try test fitting them yourself. Online you can configure an 05 and see what winter rims pop up.

 

I have an 06 6Mt coupe and I put on 17" ASA JH3 with the Dunlop M3 winter tires... so far so good. They clear the calipers just fine...PM me if you want to see pics....