modMonkey

Previous setup: 17x8.5 +54 Square 245/40/17
New setup: 17x9 +40 255/40/17

Stock Fenders:
- Front fenders rolled, slightly flared
- Rear fenders rolled
- Bumper tab relocated
- Bumper trimmed

Camber:
- Front: - 2.8
- Rear: - 2.0
I will most likely add camber at some point, haven't done so yet because I wanted to see how it was wearing via pyrometer

Currently ride height is set ~1" lower than stock. Car is used for HPDEs.

I've had this setup sitting around for a while, decided this past weekend to fit it and see how it feels. Given that this is a popular setup, I was hoping someone would be able to address my fitment concerns. So far the biggest issue I see is clearance at full lock. Visually, it looks like if the suspension compresses at full lock, it will most certainly be damage to the front fenders. Do people find they have to aggressively flare to guard against this?

CKit

Most people with 17x9s have higher offset to avoid this problem.

CKit

Also, what spring rate?

Antonov

Not difficult to fit, would be helpful to include a photo if your front fenders.

andrewhake

Sorry it isn't directly related but reading this thread had me thinking about something I have wondered:

Is there any particular reason that people run anything larger than 9" wide when using 255/40/17s? Not that it is major concern, but anything larger and it seems like unnecessary unsprung weight is being added and fitment becomes more difficult. I can understand moving to an 18" wheel to be able to run 265 tires. Are people doing this just to get a certain wheel face look?

Sebring AP1

Wider wheel is more grip. Better steering response too when done within reason. a 10" for a 255 is faster than the same tire on a 9. proven countless times.

andrewhake

I understand better steering response but wider wheel is more grip doesn't make any sense to me. Many tires have different actual sizes than 255, especially with R-compounds it seems, so maybe 10" is actually just a closer match? 255mm is 10" I suppose, so overall I guess I understand. Looking at 255 RE-11s on OEM 8.5" wheels it seems like they would be slightly stretched on 10" wheels though. But I guess the actual size of 255s throughout different types varies quite a lot. A change in the feel or responsiveness makes sense but does the wider wheel really make that much better use of the tire? Thanks!

Carbon Blue

a wider wheel = more mechanical grip, An 8.5 wide wheel with a 255 will "fold" or flex more during turns since there is more "unsupported" rubber. The positives of running wider wheels greatly outweigh the negative effects of unsprung weight etc.

CKit

I don't know the answer to the question. Depending on the application, sometimes more tire is the answer. Sometimes drag of wheel / tire size becomes an issue at high speed in a momentum car and there are diminishing returns, though.

Maybe one of the professional or semi-professional race guys can chime in?

modMonkey

The next readily available offset was 17x9 +63 and they would not have cleared my brakes.

13kg/mm or 728lb/in all around.

Sorry for the poor quality, its hard to capture depth. I can try better pictures this weekend if these are vague.