FWIW, for the summer, I use a set of 17x9 Rota DPTs (5x100, +42 offset) with 245/40/17 Dunlop Direzza Sport Z1 Star Spec tires. I also have rolled and pulled fenders all around. I'm currently using stock springs and struts on my 2007 WRX (I'd eventually like to upgrade the suspension) and I have zero clearance issues in all directions. I wouldn't consider my tires to be stretched by any means - they're just slightly less than vertical/square.
If you're going for the "hellaflush" look, you might have better luck gathering information for extreme fitments over at NASIOC.com.