What tire width are you trying to fit? 17x8" works ok for 245/40/17. You don't really need the extra width until you go for 255/40/17 and beyond. If you do intend to go 8.5" of width or more, I'd stress offset. It really makes fittment a lot easier the closer to stock offset you can find.
I run 255/40/17's on 17x8.5" +48 rims. Rear fenders need a slight roll but otherwise pretty painless.
Also note your auto-x class can change based on tire width. I think 245 is max for what most people run (stock turbo, etc).