I need new tires and am debating between 245x40x17s and 235x40x17s for my stock BBS rims on my '06 STI. I have stock springs/shocks and Whiteline front/rear sway bars. I will likely be getting coilovers in the coming year. I would love the extra 10mm width for better traction but am concerned a bit about rubbing (esp. in the rear) with the 245s under high speeds/heavy loads. Thoughts?
i had 245/45/17 on my old stock suspension sti, had no rubbing issues even with someone in the backseat. You shouldn't have any issues with 245/40 on the stock suspension.
You will not have issues. Lots of STis are running 255/40/17's on stock or similar to stock (dimension wise) wheels with zero issues.
The only thing with running that wide on our stock (narrow) wheels is you'll get some "bowing" of the tread area, as a result you'll see more wear down the middle of the tire, and you'll get a "squirmy" feel through transitions because the tire can kind of roll back and forth on the wheel, if that makes sense. On the street it wouldn't matter much but I know what you'll be doing with them. I've done wider than spec in the past and that was my experience. On the 8.5 SSRs (they might be 9, I can't remember exactly), the 255s are wearing perfectly even. But with their different offset I had to roll the rear fenders. Car's stance looks much better w/ that offset though. I've also done narrower than spec on the SSRs and the shoulders end up wearing prematurely, where they are to thread while the center still has alot of tread depth. 255 on the 8.5 seems to be the magic combo for me at least.