GoRacer

iTrader: (2)

I've decided to stay with 17's for weight and tire selection. Asking for personal experience "only", please.

Anyhow people mention tracking and darting problems from going to wide up front but the two people i've asked with 18x10's F&R have had no problems.

I'm trying to get experience and not oppinion and we can all benefit from this. No one likes regreting their decision!

btw, My wheel choices are:
RH CP035 (white), Fikse Mach 5,
Works Meister S3 (Maybe white center)
Amount of tax return may be deciding factor, sigh.

nocab72

On all fours, I've got SSR Integral A2's 18x9 wrapped in 255x35x18 Toyo's now. I'm shopping for a new setup now. Wider in the rear x10, will probably drop down to 17's as well since none of the tires I want to run come in 18's.

K

mp5

iTrader: (3)

I,m running Rpo1 9.5 all round with Toyo 255/35 f and 275/35 r
Fitment issues with coilovers, none whatsoever,even with a low 40 mm offset,lots of tire at the rear with space for more as the upgrades come.

I will confirm the dartiness with a bigger wheel/tire up front,especially when braking from 120 ,part I,m sure to the extra 8 pounds of weight.
A 8.5 inch rim running a 255 up front would be optimal,but the deal was right and the "look" is right on.

My next set will be 17,s and will be a "track set" so will be looking for max perfomance and tire choice. C














Disclaimer 120 mph was on a closed circuit dont try this at home

Jerk_Racer

For a short while I had 16x8 +30 shod with 225/50 Advan A032R's up front with stock '89 T2 wheels with crummy 205/55 tires in the back. I didn't like it. The front stuck way to much in relationship to the back. They caught every rut on the highway and autocross wasn't much fun. The back would rotate while the front stayed glued. What was I thinking? I guess I wasn't. I just really wanted to use up the last of the tires in the rear on the track. These days I go with 16x8 +30 all around with tamer AVS Int. 225/50. It's much better now.

SleepR1

FD Rx7 Road setup:

9 x 17, 45-mm SSR Integral A2, 255/40-17 AVS I's all around. This is perfect for road and autocross use, but a bit nervous through the high speed road course work, and some really fast autocross courses. On the road, the grip potential is overkill, and never gets close to the limit, unless you take an off-ramp at ridiculously fast speeds (it's ok they're usually banked anyway ) Love the benefit of rotating tires at any corner (with non directional tires). I also run a fifth full size wheel/tire for drivers eds, in case I get a flat on the way to the track (now that I sold my track setup).

"Old" Track Day setup:

8.5 front, 9.5 rear x 17, 42-mm offset SSR Comps, 245/45-17 front, 275/40-17 rear R3S03s. The increased understeer is a godsend, and you end up relying on it. The confidence inspired by the large rear tires help with mashing the gas through places where others with same size tires, need to delay mashing the gas to the floor. Overcook the entry? No problem lift a little, and let the nose tuck in, and you're back on the "line" Outstanding setup for high speed track use. I sold this setup to Jaymz, so I'm back to re-learning how to track-drive FAST with same size tires all around.

My recommendation for anyone just driving on the road (no "crooked" track time), is to go same size tires all around. The practical benefits of tire rotations, and not having to deal with two different sized wheels/tires shouldn't be underestimated. The handling is preserved (no increased understeer), and the car just plain looks better with front tires as wide as the rear tires. The SleepR1 fitment has proven itself as a good way to go.

For those looking for a more radical same-size wheel/tire fitment, try the artowar2 fitment of 265/35-18, all around on 9.5 x 18, 47-mm offset; or the maxcooper fitment of 285/30-18 all around on 10 x 18, 50.8-mm offset; 2.5-inch coilspring will be needed for the 285/30-18s to fit up front.

mp5

iTrader: (3)

285/30 18 is that a street or track setup?
would that give some darting problems?I get some on a 255/35 running a 18x9.5 front wheel.

C.

GoRacer

iTrader: (2)

Both MaxCooper (track)FD Racer (street)run 18x10 & 285's F/R but I don't remember either of them complaining about darting or tracking. Maybe they can reply to this and correct me if i'm wrong.

I wanted to run 17x9.5-F/R's as well and figured I could still stagger the tires if I didn't like the same size. Maybe the same size F/R is more popular on the track and the staggered setup is more forgiving on the street?

maxcooper

Alignment, wider tires, certain tire designs (large tread blocks at the periphery, I think), and offsets other than +50mm will contribute to dartiness in the front. It is reasonable but noticable with my 17x8.5" +40 245/40-17 setup on the front. Despite the correct offset, my car is pretty darty with the 18x10 +51 285/30-18 -- definitely "falls off center" more easily than the 245 street tires. I imagine tires have a lot to do with that as the 285s are R-compound tires. Alignment makes a big difference, too -- more toe out in front (less negative or more positive) will destabilize the front end, but helps turn-in.

I have driven on the track with the 245/265 and 285/285 setups and the smaller fronts make the car understeer more. No surprise there, and I am sure you could change the setup (springs, sway bars, alignment) to account for the difference. I don't have tire temp data, and the car feels well planted with the 4x285 setup, but I do tend to get rubber build-up from "marbles" on the front tires, while the rears are usually clean. That might mean that the fronts are too wide and don't get hot enough, or that I just work the rears harder with the power and due to my setup at the time. Actually, I did have the car setup with a lot of understeer the last time I was out and the fronts didn't have the build up. Perhaps it was just the setup working the rears more before. I talked to Tri-Point about sway bars recently and they suggested that I might get better turn-in with narrower fronts. However, the stick from the wide tires all around is wonderful (very noticable increase in traction over my old 245/45-16 R1 setup on stock wheels) and the widest possible tires was one of the recurring themes from Mark Donohue's _The_Unfair_Advantage_ book, so I think I'll stick with them. The 50/50 weight distribution suggests the same tire front and rear is appropriate, but I have heard reports of 48%F/52%R from FD owners with cages and junk removed from the engine bay, so perhaps at that point a little more rear tire is in order.

I would think that as long as the widths are within 20-30 mm, you won't get severe understeer. 225/275 or something might be too much, but 235/255, 245/265, 255/265, or even 245/275 should be fine. Lots of oversteer or understeer sucks, but a little bit either direction is usually no big deal. With stiff springs from the common coil-over setups front and rear, you'll probably end up with some oversteer anyway, so perhaps wider rear tires will swing the balance back toward neutral. Different people like the car to be setup differently anyway, so perhaps it is best just to get the main parts you want and play with sway bars or springs to get the balance you like. There is certainly more room for big tires in the rear, so maybe it is smart to go big back there for traction under power and just tune to get the balance you prefer.

Confused? Me too, but it seems like the best approach is to get the wheels and tires you want and then tune your way to a happy balance. There are a number of variables, so your experience may differ unless you have the exact same hard parts. And even then preferences play a role.

Everyone wants the setup they invested in to work well, so I doubt you'll get a lot of "my setup is wrong" posts. And even then, it is likely that other parts will be changed to fix things, rather then replacing the existing upgrade parts. For a street car, rubbing is worse than screwing up the balance.

-Max

GoRacer

iTrader: (2)

OK, i'm still confused!

Is the moral to go as wide as possible both front and rear and since there is more room in the rear, hence wider rears?

The RX-7 has a slow oversteer (from the driving i've done), unlike a 1st Gen' MR2 that can spin like a top. I'll take the over rather than the under but both can cause an accident. At least oversteer won't be a head on one.

Under and Over steer explained, click "here".

inukai

Hi GoRacer

Thank you for your PM.

Where do you run mainly?
If your target is just the track time, 18 inches is better than 17's.
But that depends much on tire brands.
A048 225-50-16 has much tire grips than street radial 255-40-18.
In Japan A048 245-40-18 in front and A048 265-40-18 Rear
is thought to be the best.
But 18 tires are very expensive.
Tires are one of the suspension components.
If you get just 18 tires on your stock FD,
you cannot get better record time than fully suspension and bushing modified 17 tires FD.

My FD is CP035 17 inch 9.5 J 33 mm offset
and A048 255-40-17 for all the wheels.
I want tobuy 18 inche tires.
But 18 is about $100 more expensive than 17 per piece.
I use 1 sets of tires every month.
I cannot afford 18 inch.

If you run manly on the street, go ahead with 18.
18 look better than 17.
but you had better not get wide in fromt.
Road condition in Orange County area is not so good.
I wouldn't get 255 in front even in Japan.

Then, tell me where do you run mainly.
And tell me the tire brand you are thinking of.
What damper do you use?
What suspension mods?
Have you replaced bushings?
What year model?

I hope I can help you.

Thanks

GoRacer

iTrader: (2)

Thanks "MaxCooper" for the alignment and swaybar info and the feedback on the 285's up front! I'm embarassed to admit, I had to read it a few times but good stuff. You dude!

Inukai:
I run mostly on the street ('94 Touring). I haven't had the money for track time this year, although i've seen some drag races. I have JIC-Magic SF1's, new bushings, stock sway bars, M2 toe link & trailing arms but very heavy chrome wheels. I run Yokohama A032 tires (they don't make 18"). My other tire choice is Toyo T1S. I don't know what tire A048 is? I don't think that is sold in the USA.

I thought all the race cars ran 17x9.5's like the CWest car but FEAST must be running 18's on their race RX-7. I look at the Japanese used car dealers alot and almost all the street cars have 17's with 235 & 255's.

Yes, the roads are bad with pot holes, speed bumps, speed dips and steep drive way ramps. Lowered cars can get destroyed over here. I am hoping to get some track time at Willow Springs next year. I allways wanted to race my motorcycle there but never did.

If you are going to sell your CP035's let me know how much you want for them (PM me). But if I could afford it, i'd some get 18" Work Meister S3's!

SleepR1

The poll looks like a toss up...It will be your personal preference really

FD Racer

I get some darting with my 18x10's with 285's all around while braking from higher speeds on uneven roads. It's not even that bad, you just have to be ready for it. The amount of grip with the increased contact patch is very noticable, it really sticks well. The only thing else I could complain if I had to is the fitment. If I could have them tuck in more, I would. Many people tell me I'm on crack when I say they stick out a bit.

DomFD3S

Inukai,

You use 1 set of tires every month??? Wow.

whitekingsnake

I was under the impression that wide in the rear and narrower in the front was the most ideal setup. The formula 1 cars use this setup.

I was thinking about putting 245/45-16 on the rear and 225/45-16 up front( stock wheels). No track events, just terrorzing country roads.

mks

The formula 1 cars have the widest tires they are allowed to use according to FIA regulations, simple as that.

whitekingsnake

So you're saying if they were allowed to have the same all around they would?

If you look at the Ferrari 360 modena on Ferrari's website the rear tires are wide as hell and the front are like street bike tires. Why would they use this setup?

GoRacer

iTrader: (2)

Aren't Ferrari's and Porsche's rear engine cars?
Wouldn't wider rears compensate for the pendulum effect of swinging the heavy rear end around?

The only other perfect 50/50 weight car that I can think of is a MR2, which is a mid engine with same width fron and rear tires.

Ferrari Enzo
2767lbs & 660HP
245/40-19F & 345/35-19R

Porsche GT2
456HP
235/40-18F & 315/30-18R

maxcooper

Ideally, your front/rear tire width ratio would match your weight distribution ratio. That's why rear-heavy cars have wide rear tires and one reason why front-heavy cars usually understeer like pigs. No one wants to put big wide tires on the front. Well, except racer/engineer Mark Donohue, who found that it made one of his cars faster. I think it was a front-heavy stock car, IIRC.

The FD is 50/50 with a driver in it, though obviously it changes as you add/move/remove stuff or eat too many cheeseburgers. The advantage of mid-engined cars is generally that they have a low polar moment of interia since the heavy engine and driver are near each other. A low polar moment of interia makes it easier to change the direction the car is pointing. Lowering the polar moment is one of the reasons why using a small battery or relocating it to the bins is a good mod on the FD.

-Max

Chronos

what do you guys think of 11" tires??
I think I might get some and fit them with the RE Amemiya GT Kit.





Only trick is finding light tires in 11" width with the right offset...

Btw, if any of you guys are looking for the best looking and lightest tire to use with a stock body check these out: http://www.wheelspecs.com/specs/wheelmodels/467

It just kills me that I won't be able to use them with the GT kit...the look is absolutely perfect for my tastes and they are simply the lightest wheels that you'll find w/o going extremely expensive forged Mg, however they're even lighter than some Mg wheels.

SleepR1

The Buddy Clubs don't come in the right offsets for our cars (at least the right offset with proper clearances). The Enkeis do but only in 18s. They come 9.5, but don't recall the offsets?

SleepR1

Currently the lightest wheels for the FD Rx7s for stock body work are the SSR Competitions. The 9.5 x 17s in 42-mm offset weighed (by me) @ 16.5 lbs. There is no wheel out there will touch this weight. They're priced right at the Tire Rack for $409 each. Maybe Luke@Tirerack can get us a group price at the Rx7 Revolution for SSR Comps in Competition Silver ? FWIW I tried the 9.5 x 17s, 42-mm offset with 275/40-17 Hoosiers up front. They fit with no rubbing, and I have H&R Springs (lowered 1.25 inches all around).

maxcooper

I had the same weird typo twice in my last post. I meant 'inertia', not 'interia' (whatever the heck that is).

If those weights are correct for the Buddy Clubs, those things are feathers! I am not saying those weights are wrong, but be careful who you trust about wheel weight specs. Steve Cirian (http://www.scuderiaciriani.com/) had a hell of a time getting good weight info when he was shopping for wheels. It is worth a read on his site to see how wrong the estimates can be, even from the wheel manufacturers.

My 17x9.5 Volk SE37Ks weigh 16.6 lbs with the center cap and valve stem. My scale reads in 0.2 lb increments, so it could be 16.5 . I do think the SSRs are a tad lighter from what I have read, but they are about the same weight.

-Max

SleepR1

Practially the same weight probably, Max The Comps were just cheaper

Chronos

What do you mean by proper clearences? I'll be using the RE Amemiya GT kit above, so I'd actually prefer the wheels to stick out instead of "stick in". Anyways, here's some pics of them on FD's...Maybe they just photoshopped them to fool us, hahaah.