Originally Posted by Mach V Dan
I'm thinking something like +45.
I would highly advise staying within 2% of stock diameter. The 275/35R18 is closer to stock size, and will probably be an easier fit because despite being wider than stock STI tire, it's 0.5% shorter, instead of being 2.6% taller. 265/35R18 is still less than 2% smaller than the stock STI size, and it's actually EXACTLY the same as the stock 235/45R17 WRX size tire.
We've departed from wheel and tire fitment here. Let's stick to that topic in this thread.
Just to be clear, you need the spacers with that particular wheel in that particular fitment. Many other wheels with the same size and offset will not require spacers.
Why are you so focused on the 10" wheel width? For a 265 I'd go with a 9.5" wheel.
Greatly appreciate the response. This will be going on an '11 WRX hatch, sorry for not clearing that up earlier. As far as why I want to go with a 10" wide wheel, it's more a question of why I wouldn't. Availability is a non issue, and the extra .5" isn't a dramatic difference in fitment from what I see. Please correct me if I am wrong. An unknown factor is if running that extra .5" (vs. a 9.5" wide wheel) may deteriorate handling/performance in some way. It may sound silly, but it's also a matter of being unique in a way. I see 9.5" setups all day, but not much in the 10" wide category.
So the intended setup now is a 18x10 wheel, ~+45 (will research the offset more before actually pulling the trigger), with 275/35/18 tires. I'd imagine a fender roll is definitely needed- I'd like to avoid pulling any fenders if possible. Also would like to be able to bring the steering to full lock and not rub on any suspension parts or splash guards.
This isn't a very familiar territory for me. When I had my RS, I thought the 16x8 wheels were pushing it