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I tried researching some past threads, but I couldn't find any on 255 tire square setup for the IS-F. My goal is to have a balanced setup and some people say to go the 275 width, but I don't want to roll my front fenders. Will 255 be a good idea? Has anyone done this? Any help is appreciated
I ran a 255/35 on my old 19x10 +38 setup in the front without issues or modifications.
Currently running a 19x9 +35 in the front also with a 255/35 and again, no issues and no modifications needed.
What's the benefit of a square tire setup though when the wheels are staggered? You still cannot rotate them. You should go with wider tires in the rear.
Ya, I might have to buy new rims, but from what I've read (including RR Racing website), a square setup gets rid of the understeer apparently, but this is why I am asking. I have no idea where to go with it, so I just want to see if it was even possible and how the car handles with these dimensions. I think I may just stick to the stock tire sizes this time around, but if I can get away with a square setup on the stock rims, I want to try it out. I already tried the 245/275 staggered tire setup and I liked it, but I like how more nimble the car feels with the stock tire sizes.
Do you plan to track the car? If not, I don't think a square setup is all that necessary for the performance on the street.. Since you have a 2012, you can easily run a 255/35 up front to go with the 275 rears. That's my current setup and my car turns pretty darn good now (I also have Penske coilovers). At the track, it does still understeer at the limit though. Now that I'm getting faster, that's what I'd like to correct when I eventually get some track wheels/tires.
Figs is running non staggered setup. I think he's running 265s. I cant recall which of his post but he replied to recently where someone was asking about staggered setup, why he did it and such. Might be worth searching for his posts.
Figs is running non staggered setup. I think he's running 265s. I cant recall which of his post but he replied to recently where someone was asking about staggered setup, why he did it and such. Might be worth searching for his posts.
Yeah, that was my inquiry to FIGS regarding the 265 square tire set-up. Here's Mike's response back to my question:
Originally Posted by FIGS
I would say I favor a square setup on track because it makes the traction limit more predictable and relative tire temps the same plus weight vs traction of the wider wheel setup has better dig characteristics on throttle. I actually still miss the 245 (r-comp) and still not convinced the weird shape of the R888 and its transition behavior. The OS Giken will push right through the apex with grip under acceleration so I never need to worrry about the back end swapping up. Even when the rear end does step, its extremely settled and easy to get back in line thanks to the changes we have made. Larger tires slow everything down and the skinnier the tire and lighter the wheel, the better the F handles as we have it setup. If I go wider I find there is not enough power to take advantage of it, at least with the tires we have tested. The 305 street tires we could get to break loose, just not the stickies so I think it really depends on the tire, the air pressure etc. Add on top of that the amount of bumpsteer and camber run in the rear and there are too many variables to make a generalization. When dialed in our car has so much grip that you start to weigh the consequences of losing it and usually I would rather take home the car in one-piece than "win " a track day.
To the OP. First, you can't roll the front fenders, they are already rolled. Any contact would be from the fender liner. Second, what year is your ISF. MY to 2011 had 8" front wheels. I would not run a 255/35 tire on a stock 8" wheel. Later ISFs had an 8½" wheel that will carry a 255/35 front tire. I am not running a square setup, but I am running a 9" wheel in front (+50 offset) with a 255/35/19 with no rubbing.
My IS-F is a 2012, I want to use the stock rims, I think it is 8.5". I understand what I am trying to do is a little wrong, but I want to try the square setup and see how it goes, and I do go to the track so this is worth while to me.
I am expecting the car to be more neutral at the limit, is this a wrong assumption? Otherwise I will probably just get stock size super sports and call it a day. BTW, thanks for all the help to everyone, appreciate the help
Running a 265 square set up. 265/30/19 all around.
RR-Racing runs a 285 square set up! 285/30/19; with slight modification to front bumper and install of quick release tab.
Both set ups require a roll/shave of rear fenders.
A few members have attempted 265/35 and even 275/35 square set ups for the track, and most say there isn't any fender modification required, even if they're slightly lowered. From what I gather, the majority are using either an 18x9.5 or 19x9.5 wheel all around, with offsets ranging from +38 to +45 safely. It will require test fitting of the wheel first to make sure it can clear the calipers. Secondly, tire choice becomes a big factor, as some manufacturers either sit narrower or wider, which will affect spacing within the wheel well and if any fender modification is necessary. And lastly, will you be adding performance modifications? 255/35 all around will probably not give adequate traction, as I've read from a few users that their 275s are not even hooking with full bolt ons (intake, header, exhaust) and the available tunes.
I currently have 18x9.5 +40 with 275/35 tires for the track, and will be seeing how everything plays out once all the parts are installed and I can gain some more track time this fall.
I'm glad you posted this thread. I was going to ask the same thing. I went to Discount the other day and discovered that I could run 265s square on factory suspension, and factory rims. Mine's a 2010. Why not run 265s instead of 255s? And can you not rotate all 4 tires even though they are a square setup?
255 tire square setup?
