You need conversion spacers. 2007 STi wheels were 17x8+53, 5x114.3 PCD, 56.1 center bore.
Spacers. Note that it's a pair of 15mm and a pair of 25mm. Wider goes on the back.
http://www.ft86speedfactory.com/isc-...l#.WU66KXgazCQ
This will effectively make the front wheels 17x8+38 and the rear 17x8+28. Both of which will fit just fine. You could run a 215 to a 235 tire with no issues. 245 will start to be pinched on an 8" wheel.
Edit- those are apparently on back order. Here's some more.
http://www.b2autodesigns.com/product...oducts_id=9059