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FC 18" wheel/tire fitment question

Old 02-12-16, 02:38 PM
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FC 18" wheel/tire fitment question

Hey guys just looking for a little insight as to what offset range would be best for my upcoming wheel selection for my FC.
I would like to run a square setup of 18x9.0-10.0 wheels, 255 width tires. Will be running +30mm fenders front and rear. Not looking to run any obnoxious amount of camber.

What range of offsets should keep me from hitting fenders/springs?

Any pictures of similar setups would be great.
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Old 02-12-16, 07:03 PM
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You can run 18x9 all around with stock fenders. You'll need to be in the +24 range. 235/35/18s will fit in front easily with most coilovers. 255/35/18s will start getting tight, but doable with over -2 camber. Coilover are needed to run these with stock fenders.

This is on 17s, but same setup. 17x9 +24 on NT01 (huge) 255/40/17 tires and stock fenders with a roll.



If you are going to run 30mm fenders, you are going to need spacers, and/or wheels with close to 0 offset.

Last edited by LargeOrangeFont; 02-12-16 at 07:06 PM.
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Old 02-13-16, 02:32 PM
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My current setup is 17x9 +24, 235/40 front 255/40 rear, stock fenders, very slight roll up Front, ~1.5" drop all around on tokico blues/intrax springs. No camber adjustments done.

Once i move to the wide fenders, coilovers will be happening. I would like to keep camber to -2* or less and to avoid using wheel spacers if at all possible.

How do you like that tire setup? Fitment looks great on your car BTW! Those nt01's definitely look beefy for 255s
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Old 02-13-16, 10:09 PM
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Well you already know what to do then! You are going to need to wait until you get your fenders on before buying wheels if you want to run little to no spacers. 9 inch wheels with a 0 offset will be in the ballpark of where you will end up. The extra space coilovers give you won't even matter at that point.

That tire setup worked pretty well. 255 NT01s are nearly as wide a some 275 tires! I now run 275s all around with 30mm shine front fenders and pulled rears.

Last edited by LargeOrangeFont; 02-13-16 at 10:13 PM.
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Old 02-14-16, 11:02 AM
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I have a pretty good idea, but its always best to ask those who have real life experience with fitment before spending the money on a nice set of wheels.

Would the offset i need be the same for a 10" wide wheel?

How tight are the 275's up front? I considered going to that size but figured I would be pushing it even with 30mm fenders.
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Old 02-14-16, 05:45 PM
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You have to decide what you are trying to do with the wheel and tire fitment.

It sounds like you are building a bad-*** street car, in which case you will probably want it kinda low so it looks good instead of looking donked out on 18s.

The issue with the FC and low is the front end cannot take too tall of a tire or it rubs on the uni-body above the front fender.

255/35-18 is the size that you want.
It is 25" tall which is about as short as you can get in 18s until you get up to the 285/30-18 (which is going to take a lot of work fitting under +30 fenders on the FC).

Many tires in the high performance street and DOT-R categories available in this size.

265/35-18 will work if you must.

275/35-18 will be monster truck fitment.

Or, you could run a lip, sideskirts and diffuser to make the FC look lower at normal ride instead of lowering.

Offsets.
Front- You need 18x10 +10 offset to fit most coilovers.
Rear- 18x10 +35 to fit widest tire with least work. Less offset to flush it out more with a fender roll/camber is possible.

If I were doing 18s on a +30 front fender FC I would get all four 18x10 +35 and use a -25mm bolt on spacer on the fronts so I could rotate.

If you don't go low (or visually low with "ground effects") on 18s on the FC it really looks really donked out. Something about the height of sidewall being so much less than the height from ground to side of the car.
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Old 02-14-16, 06:33 PM
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I'm with Blue here. As for tires a 275/35/18 will be too tall. I'd do 18x10.5 all around and run 285/30/18 tires and buy Fortune Coilovers when you get them. It will look like what my car looks like now.. These are 17x9.5, but I'm going to 17x10.5 inch wheels with this same tire and wheel offsets. Tire size is 275/35/17, but again these are race tire's and run huge for 275s. These are Shine front fenders. You can't run the car super low, but it will look low from a fender gap perspective.

You will want wheels in the +25 to +35 offset range still, and will need spacers to adjust. What you see here is a 17x9.5 with an effective +20 offset in front and an effective +25 in the rear. I'd suspect you'd need an extra 20-25mm of spacer in the rear more than what I'm running, for close to 0 offset out back with 30mm flares.





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Old 02-14-16, 08:42 PM
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I'd do 18x10.5 all around and run 285/30/18 tires and buy Fortune Coilovers when you get them.

Just like L.O.F. says if you use Fortune 500 coilovers (or another brand with long mounting ears and slot them for the same effect- I used Stance XR) there is a trick.

You move the coilover to hub ajustment (slots in the mounting ears) to full positive camber and then the usual strut top camber adjustment toward full negative camber.

This effectively moves the strut/spring out of the way so you can run a wider wheel/less offset.

This is what *would* allow you to run a 18x10.5 +15 (+35 with -20mm spacer) and 285/30-18 up front on a +30mm fender.

18x10.5 +35 with 285/30-18 will just clear in the back with a slight roll/pull and moderate camber.

It will be some work for the 285/30-18, you will probably have to shave the "lip" off the inside of the +30 fender, you might have to run more camber than you wanted to (in the -2.5deg range).

That -2.5deg camber up front on the 30 series tires means your braking won't be that great and you will wear the inside on braking pretty fast.

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

I wouldn't do 285/30-18 up front for a street car or even a dual-purpose street/track car.
In my opinion, it would have to be a track/time attack FC with rock hard front suspension and a big splitter for downforce, so you aren't cambering out of the tires usable angle with body roll.

Well, that kinda sounds cool in its own way- but it might wear me out on the street.

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Old 02-14-16, 09:07 PM
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Will be running +30mm fenders front and rear

Ooooh, just caught that you will be using +30mm in the rear as well.

So, you could run +25mm offset out back and actually have some room to the trailing arm with the 285/30-18 and run a -10mm spacer for the front for that effective +15mm front offset.

Here are pics of the problem you run into on the front of an FC.

Fender on-



Fender off-



Fender on-




Fender off-






From this thread-

https://www.rx7club.com/race-car-tec...nt-why-950879/
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Old 02-14-16, 10:17 PM
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I will add that the Fortunes allow more tire clearance than any other coilover for the FC I have seen. I did a couple other small things to get the tires to fit in front, and the only thing they hit is the sway bar at full lock. I am going to cut the fenders higher like stock fenders to get a little more clearance if I have an off at the track, but for the street it is fine.
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Old 02-15-16, 02:47 PM
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As far as what my goals are, badass street car with occasional track time.
Outside of going to 18's it will be a function over form build.
That being said rough goals will be to maximize traction and handling without turning ride quality to garbage; so not too low, not too stiff, no contact between wheels and fenders/frame/etc and suspension alignment which will not cause excessive tire wear.



I will likely go with 255/35's and a 10" wide rim. That's in theory only 1/10 of an inch taller than factory. I don't want to battle fitment alignment issues.
Along with the wide fenders i do plan on running shine auto rear bumper corner, shine auto front lip and s5 tii sideskirts with possibly feed side steps. That stuff should definitely help lower the look of the car to suit the 18's.

I will definitely look into the fortune coilovers, how is the ride quality? i hadn't began my search for coilovers yet so this is a helpful start.
from the sounds of it i will probably need spacers for the rear, I'm okay with that.

So if i'm understanding this right with the +30 fenders and wheel/tire combo stated above, i will want to shoot for wheels offset around +25 and run a 10-20 spacer in the rear to keep things flush. will +25 offset in the front affect the vehicles scrub radius noticeably? I think i recall reading the correct offset for proper scrub radius on these cars was +10-15

thanks for the replies guys! very helpful!
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Old 02-15-16, 05:33 PM
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So if i'm understanding this right with the +30 fenders and wheel/tire combo stated above, i will want to shoot for wheels offset around +25 and run a 10-20 spacer in the rear to keep things flush. will +25 offset in the front affect the vehicles scrub radius noticeably? I think i recall reading the correct offset for proper scrub radius on these cars was +10-15


On +30mm fenders front/rear and 18x10 wheels I would run a base +25 offset (so +25 offset in the rear) and a -10mm spacer in front (so +15 offset front).

If you do the "fortune" trick up front you could run a -5mm spacer (so a +20 offset front).

You could also run that +20 offset in the rear (so order +20 offset wheels and no spacers), but you might have to run some camber or grind the lip off the rear fenders or "pooch" them out when you mount them. Its a little close and any contact with the tire cracks the fiberglass fenders (unlike steel fenders).


I will definitely look into the fortune coilovers, how is the ride quality?


I had JIC FLT-A2, JIC FLT-TAR and Stance XR coilovers on my FC and I was impressed by driving ScrapFCs Fortune coilovers fast on the terrible country road we were on. I recommend them.

will +25 offset in the front affect the vehicles scrub radius noticeably? I think i recall reading the correct offset for proper scrub radius on these cars was +10-15

Yes.

That +15 offset up front means it pulls terribly to the side over uneven pavement, etc. I have felt that on an FC.
+20 offset and the "Fortune" trick will help as you are moving your steering axis to contact patch intersection.

You want as close to +40 as possible, but that won't happen with wide fenders.

I would normally recommend 17x9 +35 with 255/40-17 front and rear on stock body with the "Fortune" trick and rolled front fenders for the FC.

I understand you want the 18s and a wider wheel and I do think it will look more aggressive if low or kitted low.
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Old 02-15-16, 06:15 PM
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If you are gonna run 255s I would not even put fenders on the car personally.
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Old 01-30-19, 07:13 PM
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Almost 3 years later and I'm finally getting serious about wheels/tires/suspension again. I stumbled upon some bad coolant seals so this past year I built a new motor, pieced together a new fuel system, bought a standalone and got a base tune done before my efforts were thwarted by snow and salted roads. I expect the final setup to put down right around 400whp this spring.

Plans have changed a little, but it's still going to be a streetcar with some occasional track time.

As of now I'm looking at 17x9.5 +30 wheels, 255/40 NT01s tires, fortune auto 500 coilovers, +25 front fenders, stock rear fenders. No aero in this years budget.

I know I can get away with stock fenders, but the stock fenders arent in great shape anyways. I would rather have plenty of room to work with than be flush and smashing my tires into my fenders.
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Old 03-14-19, 09:04 PM
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Ended up going with some vs aero tamon design +25 front fenders, fortune 500's(will arrive next week), 18x9.5 +35 wheels all around(will also arrive next week) and I'm still a little undecided on tires other than they must be square and fit without major work. 255/35 federal rs-r's are my top choice at the moment, I'm just afraid they wont hold up to 400hp.
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