It will improve handling and self steering, but make the steering heavier.

Stock alignment caster is 6 degrees.

You can get an FD down to 4 degrees with stock adjustments (as little as possible), but why?

I prefer the handling from higjer caster.

Stronger self centering of the steering wheel
high speed straight line stability
higher outside tire camber on tight (lowspeed) turns

I even prefer the "disadvantages" of high caster

Higher steering effort (stock FD is a bit overboosted for me)
Rear inside wheel weight jacking causing rotation (oversteer bias) on turn in.

So I looked at my alignment report from when I last had the car aligned and it was set at 6 degrees.

so based on this, I likely can’t mess with caster. Is my tire size just not good upfront? Too much sidewall?

6 degrees caster sounds good.

Maybe its just the angle of the picture that made ot look like you had more room behind the tire in the wheel well.

Yes, your tire height is right on the edge of "too tall" at 25.3".

I had some minor rubbing on the front inside wheel well and the rear outside (though I had OEM mud flaps) with 25.3" tall 265/35-18 595RS-Rs

Stock tire height is 24.8" tall and Mazda didnt give wheel wells much room for taller tires.

@Valkyrie Front fenders are rolled and rears are stock.
I’m about a 1/2” lower than stock on Tein Flex coilovers.
Definitely not slammed, no issues with speed bumps and such.
Also, no rubbing with quick hits around town but I haven’t track the car either.
I love the meaty square look, extremely happy with this setup.


Steve

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https://cimg6.ibsrv.net/gimg/www.rx7...684f48edb.jpeg



https://cimg4.ibsrv.net/gimg/www.rx7...4fb05269d.jpeg

If you've got spares ready to go, just cut this section out of the fender liner. I am pretty sure lots of people do this for better brake and oil cooling. This whole section of my liners are missing...

Otherwise, poke two holes in the liner where it is rubbing and use a zip tie or two to give yourself clearance.


For shits and giggles, you could even try putting your rears on your front to see how they fit...

A 255/35 might actually fit better since its slightly shorter.

Anyone running HRE's "F1 Fitment" on a stock bodied FD ?

F: 8.5 X 18 +34 (235/40)
R: 10 X 18 +40 (275/35)

Seems a bit aggressive but they claim they have scanned the wheel well and it is a safe no rub fitment.

Would love to hear feedback from anyone running this setup or something very similar.

Front will require max negative camber when using stock unrolled fenders.

Rear will require around -2 to -2.5 deg negative camber with stock unrolled fender arches.

Its not an ideal or aggressive fitment width wise- just kind of the wrong offsets, wrong rear tire height and big stagger for no reason.

18x10 +50 front and rear (CCW stock fender FD spec) is a better 26 year old rule of thumb that has withstood the test of time to include Mazda Motorsports selling this size for the FD recently.

255/35-18 on 18x10 +50 will fit up front a little easier as tire shoulder is more inward from wheel offset.

The slight strech will provide direct steering feel while stock offset will eliminate trammeling and bumpsteer you get from lower offsets.

https://cimg0.ibsrv.net/gimg/www.rx7...146ddf9720.jpg

@BLUE TII - thank you for the reply, you seem you know things so I hope you don't mind if I ask a few follow-up questions:

I'd still like to go with a staggered set-up:

What about (F) 18 x 8.5 + 38 (235/40) - would this be safer and not require max negative camber ?

If the rears are 18 x 10 + 50, what size tire would you suggest ?

Thank you.

The 18x8.5 +38 with same 235/40-18 moves the tire in 4mm, so you could run ~0.75 degrees less camber.

So, probably need around -1.7 degrees front camber at 24.5" to top of fender arch ride height with a completely stock front fender.

Mind you, it wont look flush at all- but if you bring the tire out further to make it look better it will catch the fender lip when turning tight up hill and crease the fender.

18x10 +50 you can run 255/35-18 to 295/30-18. Plenty of pics of 7s with this size wheel to browse.

So, anyone heard of 2Forge?
They're "semi forged" wheels (not sure what this means) that are drilled and machined to spec. You can get 18x10s with up to a 50 mm offset. They're extremely cheap for custom offset rims.
No idea if they'll actually ship to Japan, or how much it would cost...

I am also interested in Forgestars, which have been mentioned, but I'm trying to figure out what the difference between the F14 and the F14 Drag is...

Are there any other relatively inexpensive 10 inch +50 options out there?

Or, given that I have hella camber in the front (-2.4 degrees), are there any more common offsets and sizes that I can use to run 275-295s in the front with pulled fenders?

Last year I bought a set of 4 18x11 +25 (really it was 7.25 inch backspace, whatever offset that works out to) from Jova Wheel.

These wheels are forged, not semi forged, and cost less than a set of Forgestars.

My tire installer was impressed with them, he thought they were pretty strong.

They are on my autox FD. and have about 30 runs on them.

They are well made, but I am not too impressed with the finish. It looks good, but is worn through in a couple spots.

https://www.jovawheels.com/

Which wheels? Where did you get them? There seems to be a minimum order size of 20 wheels.
How do they fit? Body mods and tire size? Pictures?

No idea how relevant this is to getting things to Japan, if you are purchasing with Yen or USD, if Japan charges import fee based on value etc...

But I started this thread in 2016 when I found $160 free US shipping 18x10 +45 for contemporary Mustang.

https://www.rx7club.com/suspension-w...-45-a-1108233/

I like the look! 27 pounds, though?
Sakebomb quotes 250 USD for shipping Titans. The total price is about three times what I want to spend, though, with the unfavorable exchange rate.

Would you recommend I went straight to 11s +45 like you are running? Your 305s on the front are almost comically wide. Haha.


I’m open to 17s, as well. I wonder how Konig Hypergram 17x10 +43 would fit with big tires.

The widest wheel and tire you can fit is going to be fastest through the corners and slowest on the straights (though braking will benifit).

This is not only a function of the rotational mass, but also the less the body of the car shrouds the wheels/tires the higher the aero drag.
On my FD its quite noticeable over 120mph.

You can add wickers (like a Z06) to guide air around the wheel/tire to help- but just putting it out for you to consider.

So, you have to decide what balance your car and the tracks you race on requires.

Whats fastest around Tsukuba isnt going to be whats fastest around Fuji...

17" wheels are a good fit for the FD.

Unfortunately, on the tire side 275/40-17 is too tall a tire for the front to turn without rubbing so you are left with 255/40-17.

255/40-17 is considerably narrower tire than a 295/30-18 or 315/30-18 (some 315 are 25.3" tall and will work up front, others are 25.5" and rub the body turning- same story with 265/35-18s BTW).

Again, theres been plenty of FDs on 255/40-17s faster than mine. But would they be even faster on wider 18s?

You can watch the evolution of the Feed Mahou FD at Gunsai and Tsukuba to see that yes, probably faster on the wider front tire.

If you go 17x10 with stock rear trailing link you have to run a bit less backspace/offset than 18 so it doesnt rub the link. Aftermarket trailing links can be spaced in on the front pivot to fix this.

Ebisu is more technical than Tsukuba, while Sugo is quite a bit faster than Tsukuba, but still quite technical.
I am more likely to go to Tsukuba again than ever going to Fuji.

The price difference for 295s is also like buying a whole extra 255.

I still have a lot of optimization I need to do on my 255s.
Braking performance is not where it should be. I think maybe my pads are too bity, which makes it harder to threshold brake (no ABS).
I use so little pedal pressure that I wonder if I have even crossed the knee point of the proportioning valve.
I will get something a bit less aggressive soon.
Of course, the track still somewhat damp and my AR1s are basically out of tread...

Actually, with my current setup (completely different coilovers, bushings, and alignment), the car feels quite neutral, so I don't feel quite as attached to a square setup as I was before.

275/40R17 was mentioned as having been a fairly popular size in the front for track days. Is the height thing an issue if you've fairly stiff coilovers (16 kg) and aren't running the car that low?

https://page.auctions.yahoo.co.jp/jp...on/o1124548009

just found that Enkei makes a 10 +45 that aren’t absurdly expensive. Think this would be a suitable fit?
might just stick with 265s because stretch and poor.

For tire height vs ride height.

You have to understand that if a tire catches a fender liner it can tear it off and jam the wheel locked- its a fast way to wreck.

If you remove the fender liners, the next spot is the headlight bucket sheet metal. If a tire catches that it can cut into it and lock the wheel or tear the tire.

If you run a lot of caster you may have to bend the rear lower front fender arch in so the tire clears.

You could make sure the shock bump stop bottoms before the tire can contact anything and/or put in steering limiters.

Its better to choose a tire as close to stock 24.8" (or shorter) as possible.

285/30-18 is another option for 18x10 +45 if you have trouble getting short enough 265/35-18.

Will probably just go with either 285 or 295, then.
i guess 285 might actually be slightly better if a 10” is all I can find, since you need to stretch it.

https://store.shopping.yahoo.co.jp/t...114345-br.html

hmm… I guess this would work, but is a bit above my budget…

https://store.shopping.yahoo.co.jp/2...-rsltlst-title
https://store.shopping.yahoo.co.jp/h...-rsltlst-title
wait, they also make two different 10.5 +45 options! and neither is absurdly expensive.

I have the 18x11 +45 TE-37s
That price is literally half of what they cost in the US.

The Enkei PF06 cost just a bit more here in US.

Both wheels are tanks at 29lbs each because they are VERY strong being JWL (JWL+R Spec2 for TE37) rated and engineered for todays 5,000lb "sports cars".

My 18x11 +45 Forgestar F14 are 26lbs.

I'm not even that big of a fan of TE-37s.
If they were the same price / weight / strength, I'd rather have RPF1s if they came in the right size.
I'll probably go with silver GTC01s in 10.5+45 once I've had enough whiskey to pull the trigger. Hope they fit. Hahaha.
At least wheels hold their value pretty well here. I've actually doubled my money selling wheels I bought used.

As for tires, Shibatire currently has a really good deal on 285/30s. They're apparently pretty good for being just over half the price of Nankang CR-Ss.
I'll be keeping onto my current wheels just in case I ever get a chance to register the car, since they don't poke out.

delete

Tires: Yokohama A052
Front: 295/30/18
Rear: 315/30/18

Wheels: Jova 18x11, 7.25 backspace.
These are modeled after Advan wheels.

These are from javawheels.com
I paid $1421.27 US shipped in July 2023 for 4 wheels, 18x11 7.25 inch Backspace.
(email windy@jovawheels.com)

Body mods:
Rear: cutout and flared
Front: Fenders rolled, mudguards removed.

The rear was flared for 335/30/18 - Hoosier A7 and Conti ECS

The fit is fine in the rear.
In the front it is pretty close, but it works fine with minimal rubbing.

https://cimg2.ibsrv.net/gimg/www.rx7...7c13fa2cfe.jpg
Front Jova 18x11 7.25 inch backspace
https://cimg4.ibsrv.net/gimg/www.rx7...9a30a55a11.jpg
Rear Jova 18x11 7.25 inch backspace