I would do 18x10 +47 front and rear with 255/35-18.

I mean, why would you want to add understeer to a chassis that already understeers with a stock square fitment?

A tiny bit of understeer on the track is going to feel safe but with a ton you will never learn how to react to oversteer and then when it happens through track conditions (independent of chassis set-up)- wham you spin.

I currently run 255 Front 265 Rear, although with smaller wheels then those proposed.

Same with Blue TII. I guess one of my main goals was to increase tire size. I'd be going from an 8.5 and 9.5 wheel to a 10 and 10.5. Yes, the tires would more in their ideal operating range with regards to maxing their recommended wheel size and tread size.

The consensus is, for track situations a 255 Front 285 Rear on a 10/10.5 wheel would result in understeer in most circumstances and snap oversteer if it (oversteer) occurs?

Aside from track situations (maybe this set would be a street only set), what would your street optimum setup be? (Mostly light to light and highway with some twisty bits for fun.)

Thanks.

^ Would definitely work well, but IMO its kinda dumb to stagger wheels/tires by such a small amount. With a fender roll you could do the 18x10+ 47s all the way around with 255/35, or even the 18x10.5 +45. Id do some measurements on the inside just to be sure as I dont know exactly how much more room coilovers provide over the factory springs.

Idealy you want to set up the tires with a slight stretch to the wheels. I mean slight stretch, that the tread width be less than the wheel width. So if you want to run a wheel that is 10" wide in the front, I would run an AD08R tire with a tread width of 9.9". This is ideal for handling and keeping the tread width flat on the ground. It also should be good for not rubbing through fenders and crisp turn in/breakaway characteristics.

I know it feels like you aren't gaining any rubber on the road by not going wider, but in reality you are gaining more rubber on the road due to the contact patch being flatter on the road with the wider wheels.

About to purchase my wheels and tire combo tomorrow, just to confirm.
I am getting;

- 18x9.5+35 on the front (Ad08r 255x35x18) running - 1.4 camber
- 18x10+30 on the rears (Ado8r 265x35x18) running - 1.2 camber

This will only require all fenders to rolled?

Since this set of wheels is my primary set (not only intended for track use), Work VS-XX wheels offer different lip sizes depending on the disk used. That is the reason for the small offset.

Front: 18x10 +47 R Disk (2" lip)
Rear: 18x10.5 +39 O Disk (3.5" lip)

So, while this thread is primarily for maximizing a stock bodied FD for track use, I'm trying to increase usable rubber and get a more aggressive staggered look without getting bonkers with wheel sizes.

Two birds with one stone if you will. Or at least that's what I'm trying to do. If this setup proves to be really poor for track usage then I will look into a square set of RP1's.

About to purchase my wheels and tire combo tomorrow, just to confirm.
I am getting;

- 18x9.5+35 on the front (Ad08r 255x35x18) running - 1.4 camber
- 18x10+30 on the rears (Ado8r 265x35x18) running - 1.2 camber

This will only require all fenders to rolled?

Correct, just a fender roll with slight pull in back (usually enough pull with happen as you roll, but it is slightly more than just folding the lip under).

The rear will fit the same as my 18x11 +45 as far as tire stretch to wheel and just stick out 2mm further to the fender (more fender roll needed) if you want to look at my pics a page back. The front will be 9mm inboard to the fender compared to mine.

Rxmfn7 ^ Would definitely work well, but IMO its kinda dumb to stagger wheels/tires by such a small amount. With a fender roll you could do the 18x10+ 47s all the way around with 255/35, or even the 18x10.5 +45. Id do some measurements on the inside just to be sure as I dont know exactly how much more room coilovers provide over the factory springs.

I agree its dumb to stagger by such a small amount so that most people won't rotate tires front to back (I actually race with the reverse stagger when I am in a naturally understeering chassis like stock RX-7/RX-8), but at least its better than even more stagger that will really push like a pig...

I just got back from helping out at a driver's school where one student was an RX-7 owner with staggered fitment. He had an experience crossing railroad tracks accelerating onto an onramp where the car snapped to oversteer.

He didn't know how to deal with that and voiced he wanted to work on learning to correct it during the school.

His first instructor took him around the skid pad teaching him to correct his stagger fitment terminal understeer with minimal, smooth steering/throttle inputs.

Obviously, that didn't help him learn to correct for snap oversteer, so again he stated he wanted to learn to correct oversteer when asked if anyone had something more they wanted to work on.

He went out with a more "aggressive" instructor who managed to get him circling the skid pad over a bump where the rear end would kick out.

Unfortunately, the transition from terminal understeer to snap oversteer was too much for the student or the instructor to correct for smoothly when he tried driving. The instructor could "save it" from spinning, but could not smoothly correct for it.

Moral of long drawn out story, you are going to have a hard time learning to drive if you stick to a "safe" understeering stagger fitment and by the time you do learn to drive you won't want stagger fitment understeer anymore.

And don't give me the blah blah blah so much power I need wider rear wheels excuse.

Most people saying that aren't even trying to maximize front fitment at all- meanwhile doing everything they can to put a wider rear on. The FD can fit just as wide a front wheel/tire as rear.

Furthermore, my FC was 420rwhp/415rwtq and could only fit 255 up front and 275 rear. I really preferred running it 255 all the way around. Understeer is slow as you have to slow down to correct for it, oversteer is fast as you have to accelerate to correct for it.

Again, learning throttle control is also part of learning to drive.

/end of I hate understeer rant maybe I need a Snickers

stompz I know this has been asked many times but I feel like I need some expert opinions before I drop some cash on some new wheels. My front fenders are rolled, rears are stock (but I will roll if required). I have Eibach Springs with Koni Yellows. I am looking for maximum performance without having to buy new coilovers, massively trim liners or alter the body lines (pull fenders). This is a street car, driven in nice summer weather ~40F+.

Wheels (Work VS-XX):
A:
Front: 18x10 +47
Rear: 18x10.5 +39

B:
Front: 18x9.5 +53
Rear: 18x10.5 +45

Tires:
A: Dunlap ZII Star Spec Front: 255R35 Rear:285R30 (narrower tread widths)
B: Yokohama Neova AD08R Front: 255R35 Rear:285R30

Looking for answers like "Wheels: A Tires: A" with any additional comments. Thanks all.

Ooops, somehow I missed the magical 18x10.5 +45 wheel in this post.

Run that front and rear with a 265/30-18 *in this order* RE-71R, AD08R, RS3(V2), 595RS-R, R1R.

You might need to roll the front fender lip under if you aren't running full camber.

(According to TireRack.com)
I noticed that an RS3(V2) runs narrower tread width then the AD08R. A RS3(V2) 265/35R18 has a 9.4" tread width vs the 255/35R18 with 9.5". Section widths are as you would expect, 255 smaller than 265. Would running front 255/35 rear 265/35 on the staggered setup I proposed (Front 18x10 +47, Rear 18x10.5 +39) keep the setup more 'square' even though it's slightly staggered?

The only reason for the minimal stagger is because of the lip sizes. Again, I'm trying to dual purpose with these wheels and I want a staggered look, but not staggered performance. I'm not concerned about rotating front to rear right now because I don't have the funds to track it often. I don't do looks over function, so I'd still like to car to handle in a predictable manor.

A RS3(V2) 265/35R18 has a 9.4" tread width vs the 255/35R18 with 9.5". Section widths are as you would expect, 255 smaller than 265. Would running front 255/35 rear 265/35 on the staggered setup I proposed (Front 18x10 +47, Rear 18x10.5 +39) keep the setup more 'square' even though it's slightly staggered?

Really tough question. You would really have to talk to someone or find pics of someone who has mounted the tires on the wheel widths you want to run and those are fairly new tires.

You want a certain look for your fitment so you better find pictures of how it looks IMO.


You can always try different sizes and send tires back to Tire Rack after mounting as long as you don't damage them- you still eat the shipping costs though. I have done this trying to find max fitment before.

ok, new to wheels here? iv been trying to learn by rearing in this forum section, sometimes it gets confusing but im trying., i am about to order some pf01 evo rims 18x9.5 all around...

Now question is, which offset to go with (someone stated that is safe all around, or is there something better?) and what size tires would i need to run? (here are the sizes and offsets offered for the wheel (http://enkei.com/wp-content/uploads/2015/02/PF01EVO.pdf)
i plan to put some r888 on them.? i did my first auto cross this month and enjoyed it so i will be doing it again, and eventually plan to put the car on a track, car is around the 25-25.5 ride height ..

i need to get rid of my 7inch wide wheels the previous owner didnt know about rims when he got these and downgraded.. it never bothered me so much till i made the power i have now.

In my opinion, autocross has pretty specific needs (there is no performance tradeoff to more wheel/tire width/softer tire).

You will very quickly regret buying anything but the widest wheel/tire you can fit under the stock body if you stick with autocross.

I suggest using the wheels/tires you have or grabbing some really cheap old mustang wheels or whatever you can find locally that fits until you have decided how serious you are about racing.

If you are serious you will want at bare minimum the decade old standby of 18x10 +50 (+7.5" backspace) and 285/30-18 tires.

I really suggest pushing the wheel width to 10.5 or 11 with as close to +45 offset as possible if you want to keep the stock body lines and the 285/30-18s tire.

The fast FD autocross guys are running 18x11 front and 18x12 rear with a flare.

If you are a competitive person the only tires to run are (in this order) Hoosier A6, Hoosier A7, maybe BFG R1S if you live somewhere really hot.

I don't care about winning so much and am too busy helping to change tires at the track, so I use streetable DOT-Rs like Hankook Z221 Ventus TD and Toyo R888.

These take longer to warm up so you are really throwing away your first couple runs, are sketchier than you would like in the starts of courses and are harder to learn to drive on (poor grip when cold, good grip when warm).

R888 are more easy going than Z221 by far as they have more consistent grip when cold/warm, but they are even slower.

To stir the pot, tread width does not equate to grip, and wider tires in back does not necessarily equate to understeer. Camber and front/rear roll stiffness distribution are infinitely more important as far as handling balance than how much tire stagger you have. You can easily have an understeery setup with 255s all around, and you can have an oversteery setup with 235 fronts and 275 rears.

Also, tire width isn't anything like as important as compound. I would rather be on 225 Hoosiers all around than the best Extreme Performance street tires in whatever width.

0.02!

the wider the wheel, and with a proper fitting tire, grip goes up. Every inch wider using the same tire class is like jumping a tire class in grip. so a 10" wheel over a 9" wheel with same principals used for tire fitting to wheel, the 10" wheel with extreme sport tires will feel the same and have the same grip as a r-compound on a 9" wheel. an extreme sports tire on a 11" wheel is like a 9" wheel with slicks.

I would rather use a 11.5" or 12" wheel with slicks if you want optimum grip. The fastest autoX guys and optima challenge winner know this. They ran 18x11.5" and 18x12" wheels on their cars as front wheel widths with the approved treadwear rating for autoX.

Danny Popp ran the widest he could fit on his 2003 corvette Z06 which won the optima challenge last year. Brian hobaugh with 18x12's won it the year before.

wheel width = more grip. check out with the supercars are all doing with their wheel widths, wider and wider and wider.

the porsche and ferrari's and such are running 12.5-13" wheel widths. they do run narrow front wheels due to the weight distribution and giving some understeer so people don't kill themselves.

Pretty tough to find 18x11 or 18x10.5 +45mm RPF1s online.

Where y'all buying your wheels from?

Forgestar F14

18x11 = 22lbs

Custom offsets/bolt patterns available and cheaper than Enkeis.

Only bummers are they don't do 1/2" sizing so its 18x11 +45 or straight to 18x12 +30 if you have over fenders- and they take a while to get.

18x10.5 +47 Enkei PF01 was offered, but I hear it was a limited run for the Mustang guys.

Custom fit 18x11 set of Forgestar F14s - Vorshlag LLC

Here are some Forgestar F14 in 18x11 that you might be able to get without the long wait to have a custom offset made.

Although they won't tell you the offsets they should be in the 50-40 range. If you call them and tell them you need 18x11 +45 offset for the front/rear of your RX-7 and you don't give a shit about their shitty mustangs they should be able to let you know if their mustang rear fitment will work front/rear for you without revealing their ultra secret offsets :jerkit:

Now you are asking the right questions. Wide wheels and correct offset.

You can widen wheels (1-2") with weldcraft but they cost some $$$ ($240/wheel). So you do a little math and a 18x10 +38mm wheel becomes a 18x11" wheel +49.9mm. This will barely clear your spring/might have slight contact with spring at full lock turning. it will require a tire that is 285/30/18. Can't have too large a section width. it will be a close fit.

18x10.5 +30mm turned into a 18x11.5" is +41.9mm offset. I did this with my car. If you run a 295/30/18 tire will probably need a little pull in the front fenders. nothing major. There are some seriously wide 295 tires though. the ad08R in 285/30/18 has a tread width of 11", the 295/30/18 has a tread width of 11.5", same with the PS2 in 295, big 11.5" tread width. you could probably get away with a 12" wide wheel.

for comparison, a falken azenis RT615K in 315/30/18 has a tread width of 11.7", it would be better to run a 295/30/18 and get basically the same tread width with a smaller OD of the tire. grip should be a wash. I might run a ad08R in 295/30/18 on my next set of tire on my wheels.

Not by as much as most people think...

Sanctioning bodies assign a LOT more "points" for tire type than for size.
The delta between a slick and an "extreme sports" tire is +28 points in Nasa competition (+2 points for extreme perf, +30 points for slicks). Meanwhile the points delta for 2" (50mm) wider tires is just over half that at +15 points. Why? Because tire type is that much more important than width when it comes to grip and lap times.
Points delta between extreme performance and top DOT R-comps (Hoosier A7 and BFG R1-S) is 20 points, still more than the points from going 50mm wider.

I'm not disputing that. I am saying that the increase in grip is not as tremendous as most people think. For sure it's not going to be a linear increase in grip with width. A 295/30-18 tire on an 11" wheel vs. 245/35-18 on a 9" wheel won't give +20% (going by tire width) or +22% (going by wheel width) more grip. Maybe 10%. Which is significant! But I'd rather be on 245 A7s or R1-Ss (nevermind slicks) than any 295 "extreme performance" street tires...

Quote:
Originally Posted by lOOkatme View Post
the wider the wheel, and with a proper fitting tire, grip goes up.

Originally Posted by ZDanNot by as much as most people think...


It has also been my experience that peak grip does not increase much with the same tire with a wider wheel.

On cars like the FD with a very good camber curve you may gain a slight increase in grip by flattening the tread profile out so there is more tire contact with the road.

On cars like Porsche, Lancer Evo, BMW you may actually lose some grip as you flatten out the tread profile you exacerbate the strut suspensions poor camber curve.

One tire does not fit all applications.

Now, we drive FDs and if you put rounded tread profile tires on and race you end up with them worn down to square tread profile at the end of the day and faster lap times at the end of the day.

------------

Additionally, if all we wanted from our tires was grip we would all run drag radials all around.

My experience has been that putting the same tire on a wider wheel-

1) Increases the turn in response.

2) Flattens (linearizes) the grip curve through the tires workable slip angle for smoother/faster transitions in/out of slip angle.

3) Slightly reinforces the sidewalls to deflection so you can run slightly lower initial tire pressures AND run slightly higher working pressures without the drop off in grip associated with ballooning tires from pressure rise. That means you get to drive a bit harder before your tires start going off with heat.

Obviously, comparing a 1/2" difference in wheel width on the same tire will have much less effect than the difference between running the narrowest wheel recommended for a tire and a 1/2" wider wheel than then recommended for a tire as BMW and Porsche do for their OEM fitments.

Its a shame,
I am quite picky with rim designs, the forgestars just dont do it for me. Unfortunately it seems like RPF1's or other "affordable" track worthy wheels dont really come in such sizes. I wonder if we can custom order with enkei? For the next few years I am keeping it as budget friendly as possible without compromising performance. I just invested a bit much on my EFR setup lol






Most time attack street/enthusiast classes limit RWD cars toa max of 285 width tires. This simplifies my question of how wide I should go really. My goal is to be square 285. This means there really isnt any point of going bigger than 11". I will be perfectly fine running a 10.5" wheel w/ 285s as a compromise also. Question still remains as to what offsets we can fit that are available.

Now as for the weldcraft.. I have 18x10+38 currrently for my rears. With a 1" increase would 18x11 +49 clear the rear shocks/toe links? I have a feeling I may need to compromise to 18x10.5

MY current fronts are 18x9.5+45 so there isnt much to add there. Maybe a 18x9.5+38 with a 1" increase will work?

This is getting tricky

if you have coilovers, I think you could widen a set of 18x10 +38mm to 18x11 and run 285/30/18 tires. be a really great set up. I am thinking about getting mine widened as well. If you do get contact on the rear trailing arm (which looks like mine wouldn't from the current 18x11.5 +42MM set up I have), you can add a small 2-3mm spacer and clear it. you will be limited to a 11" wide tire, 285 section width. if the tire overhangs much it will contact the trailing arm. again, you can run a small spacer and kick it out in the rear if had to.

I say go for it. I might do it as well next year.

Excellent info,

This does leave the matter of the fronts unresolved however