idoke1

iTrader: (5)

The answer is yes. The traction/stability control will always stay regardless of your wheel/tire setup. Unless you do the pedal dance to fully disengage it.

BEWARE: The front tires does not benefit well then the rears do when the traction/stability is on. Keep peace of mind that when oversizing the tires, you increase the sidewalls which is important to keeping the wheels in complete Balance. Increasing it will cause steering feedback and control issues. Be safe and look for the appropriate tire size for your wheels.

flowrider

iTrader: (9)

I disagree with the above statements, unless you are using the your F for drifting purposes only. Many members, including myself have concluded that the ISF is under tired in it's stock form. For whatever reason, Lexus attempted to rectify this in 2012, but the only went half way. They left the tires the same size, but widened the stock wheel ½" front and rear. I can only assume they were trying to maintain the stock OD of 26".

The RCF carries wider wheels and tires front and rear. As I indicated I ran the 245/35 & 285/30 combo when I had stock wheels, handling was much better than with the stock setup. I now have RCF wheels (9s & 10s) with 255/35 & 295/30 S-40 Bridgestones. I now have restored the tire/wheel OD to the stock 26" front and rear. The ISF seems to prefer an OD of 26". My handling is now on a whole other level.

Lou

idoke1

iTrader: (5)

I understand what you mean but had you driven hard out of a loop turn? For example: i was able to keep my speed steady @ 55mph to 60mph when doing hard loops upon exiting or entering freeway. On upgraded tire sizes on stock 19x8 19x9 wheels, max I could do was 50 mph. Any higher the car will fishtail. On stock sizes, doing and controlling short drift runs was a lot easier and better planted.

Weapon F

I agree that 2008 to 2011 ISF with 225/255 is under tired even in its stock form, when you add mods such as I/H/E you have issues putting down power that what happened to me when I added I/H/E , I went to 245F/285R setup which helped to reduce the issues associated with stock setup.

If you look at third gen 2014 IS 250 F Sport they came with 225F/255R with 204hp that the same as ISF that has additional 212hp and more weight. So yes I think it's under tired. Its my understanding Lexus did this for aerodynamics and fuel economy.

IredSF

iTrader: (3)

I run miro type 111 rims 8.5x19 9.5x19 shod with re-11 255x35 front and 275x30 rear and ABSOLUTELY LOVE THE HANDLING. Little bit of under steer at limit due to lack of square set up and I think it says a lot that this is the same tire combo on both the RCF and M3/M4.

I have pretty much full aftermarket suspension. Back end links are all figs, have f sport rear anti sway bar, front I have figs front LCA
Bushings and Ohlins coil overs and I have the 42 series steering ecu replacing the stock 40 unit on my 2010.

Car is stable responsive predictable and very tossable! I had the mods to suspension done first, steering ecu was last and likely the most important as the 40 steering ecu just had this numb feel at the limit. You couldn't tell when neutral was transitioning to understeer until you were already past the onset point. With the new ecu all that has changed. Very very communicative and excellent feedback. I know exactly what the front end and rear end are doing now at all times and can very effectively change lines by steering feel, trail brake, throttle lift or throttle on oversteer, again very responsive and predictable. Mix and match inputs as you please to get the job done it does it and feels telepathic.

The suspension mods made all the difference in improving handling and performance but I could not appreciate the extra information the suspension was communicating to me. It was MASKED UNTIL new steering ECU CHANGE allowed me to feel and appreciate all the extra information that was being presented.

mikersoft

iTrader: (1)

I currently have the same size tires (255x35 front and 275x30 rear) on OEM 2012 wheels, and I love it too.. Along with my recently installed RR Racing Penske coilovers, I was having a blast at a recent track day a Pocono Raceway in PA. The car was so easy to drive fast. In hindsight, I was sort of taking it easy on the car, since I wasn't even making my PSS tires squeal.. Yet, I passed some cars that are way faster with the right driver, including an Audi R8 and a Ferrari F430

-Mike

Weapon F

Thank you For such informative feed regarding you experience with 255/275 setup. As well as steering ECU upgrade great information.

Weapon F

Great to hear I Mike this is the sort of feedback that I'm looking for as well as supplying information to all the members who might be considering a similar setup as this . Mike did you go out with Rafi and rest of if RR racing crew ? I wish I could have made it to that event couldn't get out of work.

Weapon F

I have another question so if you guys had to choose the best street setup for DD F which would you go for

255/35/19F 275/30/19R or square setup 275/30/19

Would like to hear reason fore or against any particular setup by discussing reasons for our choices get a lot of useful information.

flowrider

iTrader: (9)

^^^^Lexus electronics on the ISF expect the front and rear wheel/tire combo to be the same, at very near 26".

255/35/19 has an OD of 26.0"

275/30/19 has an OD of 25.6"

This, IMO, the difference is too great..

With a 275/30/19 rear, again, IMO, 245/35/19 would be a better choice at 25.8"

Lou

jspecvtec

iTrader: (4)

255/275 because 275 on a 8-8.5 inch rim is way too wide for the width. Sidewalls will be weak, steering response would be slow and it will feel boaty

IredSF

iTrader: (3)

Yeah totally agree unless you are running a wider rim up front not worth it.
Yes you have more of a contact patch but you are gonna lose the precise feedback that really tells you how the cars front end is behaving due to the afore mentioned sidewall flex.

If you can DRIVE SOMEONES 255/275 set up, I think you'll be truely thrilled with how awesome the car handles .

mikersoft

iTrader: (1)

Yep..I love that 3.5 mile circuit & the track facilities.. I definitely want to go back sometime. Unfortunately, my buddy Mark & I were at lunch when they did the group photo shoot, so we missed out

I'm not sure about the staggered vs. square set-up for DD. Though, I'd like to try a square set-up if/when I get a lightweight set of track wheels. As improved as the car is with 255/275, there's still a bit of understeer, which is probably why it's so easy to drive right now.. I can turn practically as hard as I want without worrying losing the rear end.. Obviously, when it does push, I'll lose momentum and not be as fast through the turn, but that's preferable to spinning out If it gets more neutral, I'll have to become a better driver at the track (not a bad thing, of course).

Ideally, I'd keep what I have now for DD, and use the squared set-up for track only. I'll want a stickier tire for the track and it would be a waste to wear those out on the street when my PSS are such a good all around tire.. Not to mention, a more track oriented tire would probably suck in the rain. If it rains on a track day, I can just run my street set-up.

-Mike

IredSF

iTrader: (3)

Agree very mild understeer at the limit with this set up gives GREAT CONFIDENCE because of the benign break away characteristics .and I emphasize mild because you can immediately transition to oversteer if you want with

Throttle on
Throttle lift or
Trail brake

IMHO it's about perfect cause it defaults to just enough margin of error for you decide exactly what you want the car to do. Vs having to immediately counter steer if you have snap oversteer at the limit.
Just a tad bit of understeer at limit is about perfect for giving you the confidence to operate the car at or over the limit without fear of loosing the rear end( again UNLESS you WANT IT do that, and you have basically 3 ways of making it happen listed above). That is what makes it feel so "tossable", responsive care free handling when steering the rear end with the gas or the brakes.

Gearbangin

iTrader: (7)

Im currently 245/35/19 and 275/30/19 but wanted to upgrade fronts.

What do you think about 255/30/19 on the front wider tire but less side wall? Im on aftermarket rims.