RETed

Ah, okay, then in that case it'll clear everything inside.
You might have to roll the fender slightly.
With the 1.25" spacers, it's just about perfect.

Clearance will ultimately depend on what size tires you slap on those rims.


-Ted

RETed

See above.


No, you cannot use a 16" tire on a 17" rim.

With the 8.5" width up front, typically you put on a 245 or 255 wide tire on such rim widths.
If we're talking about "stretch" or hipari, then you go narrower, like 235, 225 or even down to a 215 wide tire.

With a 17" x 8.5", with stretch, you can go with a 225 / 45 / 17 or a 235 / 40 / 17.
With the 17" x 9.5", go with a 255 / 40 / 17.

I'm warning you that if you get cheap with tires, it might bite you in the *** later on.
I used to go with cheap tires, but you really hinder performance.

With that said, if you're looking for CHEAP, check out the Kumho 711's.
They should be under $100 each for those sizes.


-Ted

RETed

I don't think those specs fit.
It should rub on the insides.
A thin spacer should work to clear everything inside.


-Ted

Kingsfan

iTrader: (12)

i just got 16x8 BBS (or replica) that came from an FD and i want to put 225/45/16 up front and 245/45/16 in the rear, i figured the offset to be +50 based on a formula i found in another thread, would i need spacers on both front and back or just the fronts? and what size? there's some 25mm ones for sale that i might pick up if they'll work, thanks

RETed

If this is the case, then just the fronts for clearance.
You can use the wheels as-is in rear, but they will be tucked in...if you don't mind that look.


-Ted

Merc63

Have any of you checked to see what kind of lateral G's your pulling on those huge tires? I've seen too much tire on RX7s before that actually decrease cornering performance. You guys going to 18" wheels and larger shoudl make sure to specify that you're doing it for looks, not better performance.

While these wheels are ugly, I bought them for their offset and size to optimize the handling and balance of the car. Almost 1.2 G laterally, in fact, with quick, easy transitions left to right with manual steering. 15X7 with +25mm offset, and 225/50-15 Yokohama A008 RSIIs. This was on an '86 Sport model that was faster on the autocross track than most more 'trick" RX7s.

I didn't want that wheel style, but really all I was concerned with at the time was price and performance: "function first." At the time ('92) all the cool Japanese wheels we can get now either didn't exist, or were nearly impossible to come by. But a similar size/offset, 5 spoke, light, modern wheel would be perfect for function.

fstrnyou

Agreed, 245/45-16 is what I used to run all around. Tires barely cleared the front struts and occasionally made contact with the fender during heavy bump/compression. Enough in fact to make tiny slices where contact was made.

Positive notes---more tire means more traction

Negative notes---more tire means more traction, it seems those 245s in front causes the brake bias to get all out of whack. There is soo much more front grip, compared to the original design, the nose dives much more and the rear of the car unloads to the point that the rear tires lock up long before the fronts. THIS IS BAD. I run 225/50 all around now

Kingsfan

iTrader: (12)

thanks ted, so they will still look tucked in even with 245s in the rear?

RETed

Are you talking steady-state G's or numbers of a G-Analyst?
I don't care for steady-state G's, as this doesn't help with transition grip.


-Ted

RETed

Yep.
According to my experience, the rears would still tuck in at least 1" to 1.5" versus the fronts.


-Ted

Merc63

True, and a quick spike in Gs doesn't translate into what happens after it loses that grip. You can spike to pretty high Gs on a transition, but anything longer than an instantaneous corner can find yourself spinning into the tire wall... transition grip gets you through turn1 at SIR. Steady state is what gets you through turn 2. transition gets you through slaloms, steady state gets you though sweepers and turnarounds. becasu you can spike higher than normal in transitions, maximizing steady state can increase transitions quite a bit.

The problem I've seen with tires that are too large (and I notice your recommendations are pretty close to what I was running, at 225/50s) is that steering effort goes up and the breakaway characteristics get worse making finding and holding the limit or just past it much harder, often causing the driver to scrub off more speed than they need to. And especially with the IRS cars, too large a tire can cause tire hop from both engine and lateral accellerative forces, which you then have to compensate for in other ways.

GoCarFC3S

Am I correct in thinking that a 17x7 (+50 offset) wheel will come out 3mm closer to the fender and stick in 23mm closer to the center of the car? I think it's right, but my questions are:
1) what is the correct spacer in order to get the wheels flush with the fender (or just inside of flush)?
2) is there enough space between the inside of the wheels and the strut to clear without the spacer for a while?
Thanks in advance for the help offset gurus!

GoCarFC3S

oh yeah, this is for an 89 GXL for clarification purposes

thanks again!

RETed

Yep, I was going to mention that as well, but you know what you're talking about.
Spiking the G-sensor is not uncommon, and those numbers are practically unusable.


If all we were worried about is steady-state cornering, we'd just run as much rubber as we could fit (and afford) under the wheel wells!


The other thing that most people overlook is due to the width and offset.
Because you cannot (usually) change the inside clearances, you're stuck with that dimension.
To go wider, you just adjust offset.
What this does is causes funky loading on the hubs versus the stock set-up.
Mazda had concluding with a lot of R&D that keeping the offset high so the wheel centers are pushed all the way out - this allows cornering loads on the tires to run almost vertically into the hub.
Once you start to run really wide set-up's, these forces change diagonally.
This causes premature hub failures, and lots of race FC's with wide wheels kill the stock hubs really quick!


-Ted

RETed

Yuck.
Unless you've already got these things, I'd pass on the sale.


Stock Turbo II's run a 7.0", +40, so that's a 10mm difference.
Minimum 10mm spacer...


Not up front...


-Ted

cdnmmaguy

18" SSR D5R 5x114 8.5(front) 9.5(rear)
khumo 712 225/40/18(front) 255/35/18(rear)
theys are very new with 90-95% tread left. only one scratch on one wheel. theys wheels are 2 piece forged.


Hey, im pretty new, and just wondering if I can get a quick answer for this before they go away lol

Thanks, its for a 10AE

fstrnyou

might help if we knew the offsets......

cdnmmaguy

Sorry, im unsure of them, but theyre coming off an S2000...

RETed

No, not going to fit.
The S2000 runs damn high offsets, so there is no way it'll fit up front.

IIRC, the stock S2K fronts are either 7.0" or 7.5", but the offset is really high like +50 or as high as +60!


-Ted

clubber

I've just gotten new wheels for the car and they ended up being 17X7.5 42mm. Can I run these with 1/2 inch spacers if I'm autocrossing the car? I trusted that tirerack's wheel fitment guide would have actually worked on an FC. That was foolish. Anyway, I'm getting Falken RT 615's in 225/ 45 and I'd like to stick with these wheels if possible. Please Ted a little help for the terminally stupid would be greatly appreciated.

87 FC3S

Would these fit a FC-Work CR Kai 18x7.5 48mm offset.

clubber

The way I hear it. NO

RETed

7.5" at around +35 is minimum.
With the 1/2" spacer, that adds about 12mm.
So, you effectively end up with a 7.5" with an effective offset of about +25.

The 225 / 45 / 17 tire is going to get mightly close to the fender lip.
Be prepared to roll the fender lip a little just to get the clearance right.

Good luck!


-Ted

RETed

I concur.
You need like another 1/2" of clearance (i.e. spacer) to make it clear everything up front.


-Ted

clubber

Thanks for the info but on the subject of wheel spacers i more meant will this be secure enough to autocross without it breaking the studs off and flinging the wheel out into the weeds? I'm not sure if spacers compromise strength.