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Discussion Starter · #1 ·
Without going too far into the philosophy of it, I'd like to run 18x9 and 18x10 wheels for
DE/track work but see there are few 18x9 fr. 18x10 rr. options.
The narrow range of front offsets that work for a 9" wheel seem to be 46 to 50 if running a 255 tire on a gen2 CS. (the plan).
The special order RS98's satisfied these req. but sadly they're long gone and
for track work, would like a wheel that can be fairly easily replaced which eliminates the RS98 anyway.
Anyone with research into this combo that works and can be replaced with little hassle?
Guessing that will prob. have to go with a wheel mfg. that builds to suit ie. CCW/Fikse/Dymags etc. but not sure.
Thanks
 

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We have a set of Fikse Profil 13's we are having made as 18x9.0 and 18x10.5 Front offset is 44, rear is 38. With 2 degrees or more of front camber the wheels will be no issue to fit.

These particular ones were made for our demo car but we could part with them.

We have builds in place we could make to those specs or any other!

Cheers
 

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Discussion Starter · #3 ·
Thanks Jeff. I'm surprised 44's weren't on the fender even with -2 camb.
Interested in what front tires those were and was this without a rolled lip?
 

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Discussion Starter · #5 ·
Thanks Jeff.
Noticed a few other people were running 9" fronts while doing a search so interested
in hearing any feedback on the 9" use from others who have also fit them.
Thing is, the 255's can come in a range of widths from different mfg.,
I've seen up to roughly 10mm differences in the same size 245's of diff. brands for example.
So interested in hearing the space people have measured both strut and
fender while fitting the 9" fronts with any tire size incl. tire mfg. and offset please.
Thanks
 

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Just for a test fit I put my stock rear 18x9's on the front. They stuck out a lot and the 265s were almost touching the spring perch. Of course, these tires are taller than you'd normally run in the front too. Just looking at that I know I'd never try a 265 up front and am wondering if a 255 would be too tight. I'm not sure a 9" rim is worth it since you can't gain that much tread width anyway.
 

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Discussion Starter · #7 · (Edited)
Thanks jmazz for trying that, and it's a valid point to wonder whether it's worth it. In a street only car, probably not.
As you noticed, it's close and your sidewall was prob. about 10mm outside the lip.
Negative camber along with tight offset tolerance will allow a 255/9" though.
The thing is, depending on tire mfg. some 245's measure out to approx. a 250 and some 255's measure to a 250.
The 8.5 wheel, while big enough for a 245, is really more optimum for a 225-235 tire from a sidewall support perspective on the track.
When you're trying to use a 245 that might run large or a smaller 255, the 9" will provide better sidewall support in track conditions.
I've experienced this before in other track cars with this exact sizing and
even with -3 camber on the front, an 8.5 with a 255 will have a tendency
to roll the sidewall. If you increase the pressure to prevent that, you then
overload the center/inside pyro readings and they get greasy and go away.
The 9" helps alleviate this by stabilizing the sidewall allowing a lower pressure to be run, balancing out the pyro readings.
This is for optimum track behavior though, and the 8.5-245 combo is fine for the street/DE type environment.
 

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Wow, you've obviously done a lot more research on this already than I assumed and know exactly what you are looking for. You provided me with a lot of good information too, so thanks for your reply. Good luck finding the wheels you want. As you stated, there's not a ton available.
 

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Discussion Starter · #9 ·
Thanks. Yeah the RS98's were perfect, but their one off status would prevent
me from buying a set for a car going to the track.....S happens ya know.
 

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Ok, after a little delay, here is what we had built. We had these made to our own specs despite being told they would likely not fit....:crazy: The fronts are 18x9.0 et45 with a 245/40/18 Nitto NT-01 tire. Car has KW V3 with -2.5 degrees of negative camber. Turns out we knew what we were doing.... :taunt: which we should seeing as we are in the wheel business..... :)

Cheers
 

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Wow, that fits much better than any other 9" pics I've seen. I'm tempted to do the math to see how much the top of the tire would move outwards with a stock camber setting. Tempted, but probably too lazy.
 

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Ok, I did do the math and the camber makes a much bigger difference than I expected. Someone with a stock suspension would see the top of the tire move out at least 6mm, probably more depending on camber setting. (p.s. my trig skills are rusty so feel free to double check me)

Just more reason I wish I could do camber plates without changing autocross class.
 

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Without going too far into the philosophy of it, I'd like to run 18x9 and 18x10 wheels for
DE/track work but see there are few 18x9 fr. 18x10 rr. options.
The narrow range of front offsets that work for a 9" wheel seem to be 46 to 50 if running a 255 tire on a gen2 CS. (the plan).
The special order RS98's satisfied these req. but sadly they're long gone and
for track work, would like a wheel that can be fairly easily replaced which eliminates the RS98 anyway.
Anyone with research into this combo that works and can be replaced with little hassle?
Guessing that will prob. have to go with a wheel mfg. that builds to suit ie. CCW/Fikse/Dymags etc. but not sure.
Thanks
my .002 - OZ Allegerita seem a very good buy - available in 8"+9" or 9"+10", ~ $440 at tirerack, ~ 18lbs each.
 

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Discussion Starter · #16 · (Edited)
This is a good discussion, bunch of points coming up so,

Ok, I did do the math and the camber makes a much bigger difference than I expected. Someone with a stock suspension would see the top of the tire move out at least 6mm, probably more depending on camber setting. (p.s. my trig skills are rusty so feel free to double check me)

Just more reason I wish I could do camber plates without changing autocross class.
Thanks, and yes your skills are there, a little more than 6mm assuming -.8 to -2.5.
A stock car at stock height can get -.8 (maybe -1.0) and you need to get -2.5 or a 1.7 delta to get Jeff's clearance.
The widest point is the midpoint of the sidewall which will be 228.6 + (245*.2) = 277.6 mm from the centerline
So -.8 camb. moves the widest point .01396 * 277.6 = 3.875 mm in.
-2.5 camb. moves that point .04362 * 277.6 = 12.110 mm, so a
8.235 mm difference going from -.8 to -2.5.
Definitely significant. Not that anyone in stock class has ever drilled their top hat holes......<cough>
Like the time a friend and I went for a burger during a break at an AX and he forgot and shifted into 5th.....
in a 1970 240z.....LOL.....f'er....we all knew everyone had tweaks....and imho some of those "stock" cars are
getting much more than -.8 with a little creative hole adjustments......
All the top "spec" Miata's front suspensions don't bounce off the bumpstops yet they're "OTS" Bilsteins......
not justifying, just sayin......

Ok, after a little delay, here is what we had built. We had these made to our own specs despite being told they would likely not fit....:crazy: The fronts are 18x9.0 et45 with a 245/40/18 Nitto NT-01 tire. Car has KW V3 with -2.5 degrees of negative camber. Turns out we knew what we were doing.... :taunt: which we should seeing as we are in the wheel business..... :)

Cheers
Thanks for the update and email Jeff, was there another shop/vendor telling you it wouldn't work?
My thing is, we have to add 5mm in/out for a 255 now. (assuming the tires are perfect widths, which they're not)
Might be an issue on the inside because as you said in the email it was about 4-5mm clearance to the perch.
It will prob. work though because if I recall the 245 NT-01 runs on the large side and may be like most 255's (or a couple mm from them)
This is kind of my whole point to the thread, when you get to the
18x9 & 255, it really has to be tested and tire specific because the tire
width variations of a 245/255 from type to type alone could be the difference not to mention camber.
Appreciate your pictures and baseline of an 18x9 45et working with a 245/40 NT-01 and clearances.

my .002 - OZ Allegerita seem a very good buy - available in 8"+9" or 9"+10", ~ $440 at tirerack, ~ 18lbs each.
Thanks, the OZ you're referring to does come in an 18x9 but it's a 43mm offset rear fitment and we're talking fronts.
That said, it may work at 43mm with the 245 and -2.5 camber (see Jeff's 45mm offset pics)
but will be 2mm closer to the fender, which it looks like he has.
For a 255 though, the orig. plan of the thread, add 5mm to the 2mm from the 43mm so
you're 7mm closer to the fender than Jeff's pics when using a 255 (assuming perfect tires).
Still could work, but def. a possibility that -2.5+ camb. and/or fender roll could be req.
to run 18x9 fr. @ 43mm and a 255 tire, which puts us back at the orig. Q for someone who's actually
tried an OZ or other in that fitment because it will be very close imho.
Very close is fine, hitting, not so much......
 

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Yes, "experts" at some vendors and at a couple of other shops expressed their thoughts that the combo would not work.

I can put a 5mm spacer on the car and show what that looks like as well to give an idea what folks are looking at with closer to stock camber. That will be a couple of days as we are hosting a track event tomorrow...

Cheers
 

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Discussion Starter · #18 ·
Yeah, know what you mean, seems sometimes they view the "application guide" as cast in stone....
The 5mm add-on look/measurements would help, thanks.
Are those rears in the pic the 18x10.5 38et's?
Thanks for the effort.
 

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Here is a photo of a Fikse Profil 10 installation with probably the largest wheel/tire setup that will fit (and only on a race car).

Fronts are 18x9 ET 44 with a 7 mm spacer and 255/35 Hoosier R6.
Rears are 19x10 ET 38 with a 7 mm spacer and 295/30 Hoosier R6

Wheel dimension was specified to require a spacer so that we could adjust the fitment. We needed the 7 mm to keep the tire off the coilover spring and needed to roll and pull out the fenders to make it work.

Cheers,

 
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