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      11-13-2012, 02:37 PM   #23
gferil
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Yeah you're going to need some camber up front to fit the 265. I'm running Eibach/Bilstein suspension with no aftermarket camber plates, and have a 245 Michelin PSS up front and when I did the skid pad exercise at the car control clinic it was rubbing like crazy. Most other driving it was fine, and when I did my track day I didn't notice any rubbing but then again I was going pretty damn slow...
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      11-13-2012, 03:15 PM   #24
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Hey Finnegan, thanks for posting this thread. It's been really helpful in my quest to find the ideal sizes/offsets. It's also making me re-think buying the TE37SLs, as they are way more expensive than the EC7s which also look fantastic.

I was curious as to why you were more concerned with the rear rubbing than the front? Naively you'd think that if the front doesn't rub with 1" more wheel, the rear shouldn't either.
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      11-13-2012, 08:16 PM   #25
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Just to clarify, I wasn't worried about the wheel rubbing, rather it was tires. A 10" ET25, as a wheel, fits just fine!

Let's say we're looking at a 275/35 round shoulder tire like the PSS. On a 9.5" (tire's measured width) wheel, tread width will be about 10". On a 10" wheel, tread width will be about 10.2".

What about a square shouldered tire like an RS-3 in the same size/aspect? On a 9.5" (tire's measured width) wheel, tread width will be about 10.2". On a 10" wheel, tread width will be about 10.4".

Rated M Roadster is running a 10" ET25, with a 275/35 RS-3 on a lowered car, but is running a good amount of negative camber (-3 rear) to keep it from rubbing. I think there are plans to roll the rear fenders a bit and dial it back. (BTW, I think his set-up looks unbelievably good!)

Contrast Rated M's setup with that of kennyfrc's stock setup that's running a 275/35 PSS on a 10" wheel. Kenny's is on a totally stock setup, no rubbing, no tweaks. (BTW, that's another very good looking setup).

Section width (sidewall meaty part of the tire) is the same on the RS-3 and the PSS. But not tread width. And wheel size and the tire's measured rim size affect the tread width (~2/10" for each .5" rim increment). That's why a PSS works on the 10" wheel pretty easily, whereas a more square shouldered tire might not work without some adjustments (it will work but there is some tweaking to do).

The other thing about the increase of 1" on wheels is that the space on the front wheel well is more generous, relatively speaking, since the rear starts off at 9", and already uses a chunk of real estate. At least that's my read on the amount of available room. So the 1" change is a bigger one, relatively speaking, given the available real estate.

Bottom line, there are a lot of variables involved in fitment, as I've learned on this journey (still learning):

Tire's measured rim size
Wheel width (and impact to tire's measured size)
Offsets
Lowering
Camber (and how camber is achieved, plates vs. shims vs. lowering or a combo)
Perch location
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      11-13-2012, 10:58 PM   #26
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Quote:
Originally Posted by Finnegan View Post
I'd see if there was a way to to go with the 9.5". That's going to add about 2/10" more tread width vs. the 9" wheel with that 265/35 tire. A tire mounted on the minimum side of recommended rim sizes isn't going to work as well as mounting the tire on the measured rim size (9.5" in this case).

My thinking these days is that for front wheels, it may be even better to have a .5" wider wheel than the tire's measured rim size. I think that helps manage tread squirm and tire movement, and realizes the full potential of the tire. (Although fitting a 10" wheel on the front is really feasible.) Rear doesn't see the same lateral forces, and measured rim size works there. Stock wheels and tires have a .5" wider than tire measured rim size on the front--I think there's a reason for that.
I hate to keep on derailing from your thread (my apologies)

I completely agree with the 9.5" wheel. I completely forgot about the extra tread that is added with the increase wheel width. Even though I may screw myself over with a SCCA class (even though that may change with the letter I wrote) the car will be MUCH more fun to drive on the track and auto-x with a square set-up and massive camber

I was thinking ET 35 upfront and ET 22 in the rear. Should be enough with extra camber (i'm hopping I don't have to go adjustable control arms in the rear).

Does anyone know if 17" Wheels will fit? The only problem is that I'll be forced to run staggered

Quote:
Originally Posted by Finnegan View Post
Just to clarify, I wasn't worried about the wheel rubbing, rather it was tires. A 10" ET25, as a wheel, fits just fine!

Let's say we're looking at a 275/35 round shoulder tire like the PSS. On a 9.5" (tire's measured width) wheel, tread width will be about 10". On a 10" wheel, tread width will be about 10.2".

What about a square shouldered tire like an RS-3 in the same size/aspect? On a 9.5" (tire's measured width) wheel, tread width will be about 10.2". On a 10" wheel, tread width will be about 10.4".

Rated M Roadster is running a 10" ET25, with an RS-3 on a lowered car, but is running a good amount of negative camber (-3 rear) to keep it from rubbing. I think there are plans to roll the rear fenders a bit and dial it back. (BTW, I think his set-up looks unbelievably good!)

Contrast Rated M's setup with that of kennyfrc's stock setup that's running a 275/35 PSS on a 10" wheel. Kenny's is on a totally stock setup, no rubbing, no tweaks. (BTW, that's another very good looking setup).

Section width (sidewall meaty part of the tire) is the same on the RS-3 and the PSS. But not tread width. And wheel size and the tire's measured rim size affect the tread width (~2/10" for each .5" rim increment). That's why a PSS works on the 10" wheel pretty easily, whereas a more square shouldered tire might not work without some adjustments (it will work but there is some tweaking to do).

The other thing about the increase of 1" on wheels is that the space on the front wheel well is more generous, relatively speaking, since the rear starts off at 9", and already uses a chunk of real estate. At least that's my read on the amount of available room. So the 1" change is a bigger one, relatively speaking, given the available real estate.

Bottom line, there are a lot of variables involved in fitment, as I've learned on this journey (still learning):

Tire's measured rim size
Wheel width (and impact to tire's measured size)
Offsets
Lowering
Camber (and how camber is achieve, plates vs. shims vs. lowering or a combo)
Perch location
Lots of good information here. I run 265 RS3s in the rear with stock OEM wheels and I rub on the inner plastic wall. I had to add a 5mm spacer (running -1.5* camber)
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      11-14-2012, 12:20 PM   #27
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Quote:
Originally Posted by Kgolf31 View Post
I hate to keep on derailing from your thread (my apologies)
No problem. I posted in the "wheels" section rather than photos section because I thought there might be some technical discussion around fitment. Keep "derailing" as needed!

Quote:
Originally Posted by Kgolf31 View Post
I completely agree with the 9.5" wheel. I completely forgot about the extra tread that is added with the increase wheel width. Even though I may screw myself over with a SCCA class (even though that may change with the letter I wrote) the car will be MUCH more fun to drive on the track and auto-x with a square set-up and massive camber
Are you appealing the class for the Z4M? I may run a 255/35 265/35 set up at some point.

Quote:
Originally Posted by Kgolf31 View Post
I was thinking ET 35 upfront and ET 22 in the rear. Should be enough with extra camber (i'm hopping I don't have to go adjustable control arms in the rear).

Does anyone know if 17" Wheels will fit? The only problem is that I'll be forced to run staggered
Yes, they will fit. There's a 17 x 9.5 ET35, and a 17 x 10 ET25.

Colakitty is running 17s (but 10.5 rear). I wonder if there are any concerns with the larger sidewall, flex, and tire movement? Sidewall design, and rim width would help manage this though.

Quote:
Originally Posted by Kgolf31 View Post
Lots of good information here. I run 265 RS3s in the rear with stock OEM wheels and I rub on the inner plastic wall. I had to add a 5mm spacer (running -1.5* camber)
Thanks. Yes, lots of variables. But worth thinking through, along with objectives and needs, to get the best fit and performance.
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      11-14-2012, 12:51 PM   #28
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Quote:
Originally Posted by Finnegan View Post
No problem. I posted in the "wheels" section rather than photos section because I thought there might be some technical discussion around fitment. Keep "derailing" as needed!
As you wish



Quote:
Are you appealing the class for the Z4M? I may run a 255/35 265/35 set up at some point.
I wrote a letter to the SEB awhile ago (September 21st). And got a response back from explaining this:

Quote:
Kyle xxxx,
Your letter has been reviewed by the Street Touring committee, and a recommendation has been made to the SEB. The SEB will review your letter and the Street Touring committee's recommendation on their next conference call. Your letter details are below:
I checked the status of me letter today, #9268, and got this:

Quote:
Letter number #9268 has been reviewed by the Street Touring committee, and sent to the SEB for final review.
Basically, I asked for them to consider the Z4M for a class in ST. Since we are limited to AS/BSP/RTR...adding coilovers will bump me to BSP (which I do not want to mod to).

I'm speculating that our car will get classed into STU, which means the mods I have planned will fit perfectly. Does it mean I'm going to be competitive? Eh we'll see. It sure beats trying to be fast with no camber in RTR. Either way though, coilovers and a square set-up are coming. I'd rather have a fun and fast car that may do so-so in PAX versus a car that I just have to deal with.

There was no mention of my letter # in the November fastrack, so look for it in December!

(If you want to write a letter explaining the same thing it will help the cause )


Quote:
Yes, they will fit. There's a 17 x 9.5 ET35, and a 17 x 10 ET25.

Colakitty is running 17s (but 10.5 rear). I wonder if there are any concerns with the larger sidewall, flex, and tire movement? Sidewall design, and rim width would help manage this though.
There would be extra sidewall, but I never considered sidewall deflection. If you're maintaining accurate rollover (at the arrows) I see now harm in more sidewall. It may decrease some feel and response maybe?

Only reason I'd get 17s is the shed weight. Since they don't have 9.5" front and rear, I'm going to stick with 18s.

Quote:
Thanks. Yes, lots of variables. But worth thinking through, along with objectives and needs, to get the best fit and performance.
Agree, it's more so of just throwing as much tire as you can get on the wheel...as we all discussed prior
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Last edited by Kgolf31; 11-14-2012 at 12:56 PM.
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      11-15-2012, 11:07 PM   #29
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Very sweet. But I am biased when it comes to black wheels.
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