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      03-18-2008, 05:19 PM   #1
veearrsix
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3.0si with 18x10 BBS

I've got a set of BBS CH motorsport wheels that I want to fit to my 3.0si coupe, but when I test fitted the rear it stuck out past the body.

The fronts are 8.5jx18 ET35, and the rears 10jx18 ET40. Has anybody fitted a similar sized set?

Also does the z4mc have a different width track, or wider rear arches?
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      03-18-2008, 05:44 PM   #2
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The Z4M has a different rear offset (by something like an inch on each side). I believe the body is the same as the non-M, but the hubs sit an inch further inside the wheel well on the M to compensate for the 18x9 ET30's for the M vs, the 18x8.5 ET50's that come on the non-M.
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      03-18-2008, 09:00 PM   #3
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+1, good answer.

20 mm difference. not quite an inch, but still a material difference.
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      03-18-2008, 10:07 PM   #4
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Quote:
Originally Posted by Reach View Post
+1, good answer.

20 mm difference. not quite an inch, but still a material difference.
True ET50 - ET30 = 20mm, but 9" - 8.5" = 0.5" ~ 13mm (the difference in stock rim widths). Figure half of this difference on each side of the rim and if both cars are designed to have the outer rim flush with the body you get a difference in hub location of about 26mm ~ 1 inch.
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      03-19-2008, 12:29 AM   #5
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Geez, learn to take a compliment

It doesn't work out quite as evenly, and the wheel position can't be taken to be exact across the 2 models. So, we're arguing over a few mm, negligible compared to the original answer, which is largely accurate; though not precise. But, you started it, so let that be a lesson: never get into semantics with me.

I love the accuracy versus precision argument, heh.
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      03-19-2008, 04:18 AM   #6
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So.....

Does anyone think that the a 18x10 ET40 rim should fit on the rear of a 3.0 si?

The ofsset calculator says:
" 9mm LESS clearance on the strut side, and the outside edge of the wheel will EXTEND an extra 29mm"

Which sounds like they should just about squeeze under the arches (the stock rims sit way in under there).
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      03-19-2008, 10:32 AM   #7
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Quote:
Originally Posted by Reach View Post
Geez, learn to take a compliment

It doesn't work out quite as evenly, and the wheel position can't be taken to be exact across the 2 models. So, we're arguing over a few mm, negligible compared to the original answer, which is largely accurate; though not precise. But, you started it, so let that be a lesson: never get into semantics with me.

I love the accuracy versus precision argument, heh.
Hey, we engineer types are notoriously humorless about numerical specifications and I was just guessing based on assuming equal locations of the stock outer rim. Thanks for clearing up the actual hub spacing. So that means the stock M rims sit about a quarter inch further outboard than on the non-M (?). (precisely or accurately)
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      03-19-2008, 10:43 AM   #8
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Quote:
Originally Posted by veearrsix View Post
So.....

Does anyone think that the a 18x10 ET40 rim should fit on the rear of a 3.0 si?

The ofsset calculator says:
" 9mm LESS clearance on the strut side, and the outside edge of the wheel will EXTEND an extra 29mm"

Which sounds like they should just about squeeze under the arches (the stock rims sit way in under there).
Someone else here recently put stock M rims on his non-M and got them to fit (albeit barely). Those are 18x9 ET30 and would stick about an eighth of an inch LESS far out than 18x10 ET40's. 1/8" isn't much, but it sounds like you'd be awfully close...
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      03-19-2008, 09:48 PM   #9
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Quote:
Originally Posted by vachss View Post
Thanks for clearing up the actual hub spacing. So that means the stock M rims sit about a quarter inch further outboard than on the non-M (?). (precisely or accurately)
Not quite either

I believe its ~ 1/4inch inbound, not outbound. Since M rear wheels have 20mm less positive offset, that would mean the hub mount is closer to the centerline of the car, not the outer body.
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      03-20-2008, 01:01 AM   #10
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they will fit... im running a 19x10 w/ +35 offset in the rear of my 3.0 no rubbing...
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      03-20-2008, 08:28 AM   #11
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Quote:
Originally Posted by OH FO SHO View Post
they will fit... im running a 19x10 w/ +35 offset in the rear of my 3.0 no rubbing...
Do they stick out past the rear arches? I have a feeling its illegal in the UK if they do...
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      03-20-2008, 06:38 PM   #12
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I've finally got round to trying the wheels actually on the car, looks like they fit a treat.

8.5jx18 ET35 Front, 10jx18 ET40 do indeed fit a 3.0si coupe.
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      03-21-2008, 01:17 AM   #13
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Quote:
Originally Posted by veearrsix View Post
Do they stick out past the rear arches? I have a feeling its illegal in the UK if they do...
lets say its aggressive

im sure the +40 offset will be no problem fitting legally for you
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      03-21-2008, 12:52 PM   #14
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Good to hear guys. Nothing speaks louder than experience. Between this and the M wheels fitting on a 2.5, I think its time so say there is a bit more clearance in the Z than many of us originally thought.

Still, its a bit aggressive for my taste, but glad to hear its working out for you.
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      03-21-2008, 03:42 PM   #15
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I think 29MM out will be past the arches of the fender. I measured it at closer to 18MM difference from stock vs flush. The CSL reps I was looking at which have E46 Coupe offsets are 18x8.5 and 18x9.5 with ET 40 and ET 45 are designed to be flush on the Z4 non-m as well.
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      09-14-2008, 05:45 PM   #16
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Pix of my z4 coupe with 18" BBS ch

My Z4 wearing BBS ch's, fronts are 8.5jx18 ET35, and the rears 10jx18 ET40.




Pic showing the rear offset

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      09-14-2008, 07:51 PM   #17
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Tire Rack shows the BBS CH 18x10 as fitting the non M Z4. From veerrsix's photo of the rear fit, there is some extension of the wheel past the body panel. A good reminder that "fit" is not a precise term and is open to interpretation.

Veerrsix, what tires are you running?
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      09-15-2008, 03:50 PM   #18
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Quote:
Originally Posted by veearrsix View Post
My Z4 wearing BBS ch's, fronts are 8.5jx18 ET35, and the rears 10jx18 ET40.




Pic showing the rear offset

that looks sweet! thats exactly how i wanted my coupe to look but couldn't find a good set of used ch's on the classifieds so i settled for oem 197s...
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      09-17-2008, 05:15 PM   #19
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Quote:
Originally Posted by veearrsix View Post
My Z4 wearing BBS ch's, fronts are 8.5jx18 ET35, and the rears 10jx18 ET40.
Your Z looks awesome!

I'm thinking of doing BBS CHs on my M Coupe.
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