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      03-07-2011, 11:55 AM   #111
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Quote:
Originally Posted by onebluemcm View Post
It may be possible to remove material from the mating surface of the wheel, yes. May is the critical word. If there is not enough material left, there is a very, very real risk of a catastrophic failure; i.e., wheel flange pulling off of the wheel, wheel rolls down road unatached to car, car meets telephone pole/rock/barrier/other vehicle, you die. You'd want to speak directly with an engineer of the wheels in question about this.

More importantly, going at any wheel flange with a grinder would be like trying to restore a fine piece of art with a belt sander, or something. Do not do this!! The wheel flange, that mates up to the hub/rotor has to be as near perfectly parallel with the rim as possible. When it's out of parallel, it's called runout, this is a bad thing. All wheels will have some runout but on the best wheels it's miniscule. Aside from a CNC shop with an engineer or highly experienced operator, there is basically no practical way to remove material from the flange in any precise way. I think it would be hard to find a CNC shop that would be willing to do this simply for liability reasons.
Ok thank you for this info. I was not recommending one attempt this themselves, rather that I had heard it mentioned a few times it is possible. And it makes sense...hell we do business with an engineering company that machines 100lb shafts from billet for us which must be in perfect balance...given that it seems like machining a wheel hub down is entirely feasible...the liability however being a major concern.
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      03-07-2011, 03:17 PM   #112
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Quote:
Originally Posted by r4gs View Post
F: 18x8.5 et35 with 245/40
R: 18x9.5 et35 with 265/40

will the rears clear the inside of the rear wheel wells? calculators are showing 11mm less wheel to strut clearance.
hrmm...I actually am not sure for the rears on this one
I used to have 9.5" rears with +22 and those fit easily, even with slightly lowered suspension. However, I never checked the inside clearance, so you're gonna hafta do some homework on this one, sorry bud
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      03-07-2011, 04:08 PM   #113
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^boo thanks though. thinking the addition of 10mm/12mm spacers would be perfectly fine, but don't want to run spacers in the first instance. i need to stop myself from being tempted to get wheels!
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      03-07-2011, 06:16 PM   #114
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Quote:
Originally Posted by BTM View Post
Ok thank you for this info. I was not recommending one attempt this themselves, rather that I had heard it mentioned a few times it is possible. And it makes sense...hell we do business with an engineering company that machines 100lb shafts from billet for us which must be in perfect balance...given that it seems like machining a wheel hub down is entirely feasible...the liability however being a major concern.
I also have no doubt that this can be done and done right - I see the main logistical issues being mounting the wheel without damaging the finish becaus the face of the rim wil have to be down most likely and then it would just have to be done by someone who absolutely knows how to reference the CNC to the rim so that the finished flange surface is as dead-on parallel to the rim as possible. It's a matter of finding the right shop. And making sure there is enough material to safely work with it.

My front RAC RG63s are pretty aggressive and I do have some room to spare on the inside. Also, the fronts have more material in the flange than the rears, so at least in my theoretical head, it might be possible. I haven't contacted RAC to find out if a few millimeters could be shaved off and maintain structural integrity though. I just may do that now that we've brought this topic up though!

Quote:
Originally Posted by r4gs View Post
^boo thanks though. thinking the addition of 10mm/12mm spacers would be perfectly fine, but don't want to run spacers in the first instance. i need to stop myself from being tempted to get wheels!
Nooo! Don't give up! It took me forever to finally bite the bullet. I guess it partly depends on what you want to spend, but if you can hold on it does sound highly likely that MORR will be making an 18" version of their VS8.2 wheel. I've been constantly reminding them of what offset range would be best for the Z4M, hopefully they will come up with something that fits well. Wheels are a great mod because it's a way to but some of your own taste into it. Suspension, electronics - that are what they are, just stuff that we toss on in different combos. Wheels are something a little more personal IMO. Keep looking!

Quote:
Originally Posted by r4gs View Post
F: 18x8.5 et35 with 245/40
R: 18x9.5 et35 with 265/40

will the rears clear the inside of the rear wheel wells? calculators are showing 11mm less wheel to strut clearance.
I have an estimated 8-9 mm clearance on the inside - estimated because even though I can see it clearly, I cannot get a measurement tool up in there to get a precise measurement. That's with a 10" et27 rear. Using the wheel calculator here http://marksink.com/tire_wheel_offset/offset.html it says you have 2 mm less clearance to the strut, and the outside of the wheel would move inward by 14 mm, a tad too much IMO but from an appearance point of view, not a functionality point of view. Would it work?...me says yes Might you do better on a wheel without spacers? Probably. Based on mine, I'd say this 9.5 et35 would look great with just a 10 mm spacer, if all calculations are correct, that would set it inward about 4 mm from where mine are - perfecto!
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Last edited by onebluemcm; 03-07-2011 at 06:34 PM..
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      03-07-2011, 07:04 PM   #115
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^using ur rear wheel measurements, 10" et27, calculators show 10mm less clearance between the inside of the wheel and the strut housing compared with stock. for 9.5" et35, i'll contend with 11mm less clearance, which according to ur eyeball estimation, should still clear on the inside with barely 7-8mm to spare. on the outside, 9.5" et35 will extend outwards by 1mm over stock, so next to negligible. granted, running 10mm spacers on the rears would give the perfect, flush look, and give more clearance on the inside of the wheel. thanks for ur input!

still, really pinching myself hard not to bite the mod carrot again....
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      03-07-2011, 07:41 PM   #116
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Agreed on the numbers. I guess that's the issue - going from stock to something else, you'd kind of like to bring the whole wheel outward a bit, rather than just add width on the inside. Maybe a 9.5" et, say, 25-30 would be more ideal. 9.5 et 35 would fit, just could be better. Maybe this alone is a reason to hold out for something more optimal....I can't condone giving up on the idea though!
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      03-07-2011, 11:51 PM   #117
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^it's really a self-fulfilling prophecy. i'll keep thinking about it to no end, and eventually i will hypnotically open my wallet, drop a wad of dough, and next u thing u know, bam! new wheels.

curse this addiction!
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      03-08-2011, 12:14 AM   #118
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      03-08-2011, 07:16 AM   #119
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rG4s - why you don't use 10 -ET 35 in place of 9.5?

it doesn't work ? I bought that for my Z4 (R 255/35/18 10J ET35 F 225/40/18 ET 8.5J ET 35) .. I'm waiting for the delivery - 4 weeks. :- ( still 2 to wait.
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      03-08-2011, 08:36 AM   #120
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^isn't 10" et35 going to be even less clearance on the inside? i'm not familiar with the 3.0si offsets, but on the m's et35 in the rears with 9.5" is very close. also, i'm considering a local set which is why i don't have much choice!
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      03-08-2011, 10:44 PM   #121
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alright, thanks to nikki, verified tt 9.5" et35 will clear the inside of the rear wheel wells. question i'm having now is, front diameter is going to be 25.4", and rear is going to be 26.35". how significant is this 0.95" difference in tire diameters going to affect stance, handling, speedo error etc, if any?

am looking at a local set of m6 reps - 18x8.5 et35 fronts with 235/40 ps2's, 18x9.5 et35 rears with 265/40 ps2's. $1200 picked up sounds reasonable? 1 year old, 6000 miles, minor curb rash on one of them, no bends, cracks, peeling etc.
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      03-08-2011, 11:11 PM   #122
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According to this calculator for percentage difference between stock and aftermarket sizes in terms of combined wheel/tire overall diameter:
http://www.e90post.com/forums/forumdisplay.php?f=12

Your rear wheel/tire setup will be 1.195% off from stock. Which means your speedo will read 61 mph when it's actually 60mph. Negligible difference

BTW, the comparison isn't between your front and rear wheel/tire overall diameter. It's comparison between each corner's individual totals.
i.e., what I did above to get you that result was compare stock rear wheel spec: 18x9 +35 w/ 255/40/18's vs. the aftermarket set you're looking to get: 18x9.5 +35 w/ 265/40/18's.

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      03-09-2011, 12:05 AM   #123
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^thanks mfan, but my concern is the rear diameters are larger than the fronts, meaning won't the car 'lean' forwards ever so slightly, thus maybe having more wear on the front tires (since balance is slightly forward), and this will in-turn maybe marginally affect handling/braking? maybe i'm over-thinking things.

what do u think of the price? the ps2's have a 2005 date of manufacture though....
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      03-09-2011, 12:15 AM   #124
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Quote:
Originally Posted by r4gs View Post
^thanks mfan, but my concern is the rear diameters are larger than the fronts, meaning won't the car 'lean' forwards ever so slightly, thus maybe having more wear on the front tires (since balance is slightly forward), and this will in-turn maybe marginally affect handling/braking? maybe i'm over-thinking things.

what do u think of the price? the ps2's have a 2005 date of manufacture though....
I honestly doubt that the bias will have that much of a detrimental effect on your car, if any.

Also, I don't recommend those 2005 production tires. Rubber degrades over time, and it's just better peace of mind to get something else.
Plus, I've always felt that PS2's were overpriced and overrated. Get Dunlop Star Specs. You won't regret it
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      03-09-2011, 11:52 AM   #125
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r4gs - normally in Z4's the front tire is 40 and behind is 35 so if you take 265/35/18 behind and 235/40/18 in the front .. you will have no speedo error.
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      03-09-2011, 07:23 PM   #126
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Quote:
Originally Posted by r4gs View Post
alright, thanks to nikki, verified tt 9.5" et35 will clear the inside of the rear wheel wells. question i'm having now is, front diameter is going to be 25.4", and rear is going to be 26.35". how significant is this 0.95" difference in tire diameters going to affect stance, handling, speedo error etc, if any?

am looking at a local set of m6 reps - 18x8.5 et35 fronts with 235/40 ps2's, 18x9.5 et35 rears with 265/40 ps2's. $1200 picked up sounds reasonable? 1 year old, 6000 miles, minor curb rash on one of them, no bends, cracks, peeling etc.
I rely pretty heavily on http://www.1010tires.com/TireSizeCalculator.asp for making tire comparisons. It's a pretty handy calculator. I didn't look to see what calculator is referenced in the e90post link above, maybe it's the same or similar. 265/40 is stock E90 M3 tire size, wouldn't be too much different from our stock tire - little taller side wall, some people like that. The 235/40 is a down size from the stock E90 M3 front tire (which is a 245/40). I's probably end up doing something different with the front in place of that 235/40.

I think nearly 1" diameter difference in tire size front to back will be noticable visually and might look a little weird. Stock 255/40/18 tires all run right at 26" diameter, give or take maybe 0.1". Even though the fronts clearly will not affect the speedo, you can't make too drastic of changes up there because it could potentially affect DSC.

In general, I think a half inch or less difference in diameter, front to back, would be desirable from an appearance point of view. Beyond that, it's just a matter of comparing any desired tire sizes to what stock is just to keep diameter close for the sake of not screwing with the speedo too much or potentially triggering DSC issues.
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      03-16-2011, 11:34 AM   #127
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im running 19x8.5 et 32 with 235/35/19 19x9.5 et 27 with 265/30/19 no rub at all, setup looks great would like to be ideally @ et 25 on the rear.... the front 8.5" looks awesome with et 32, nice and flush.

receieved great advice on here :-)
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      03-17-2011, 12:24 AM   #128
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I just wished the moupe had more clearance up front... I would love to run an 18x9.5 et22 squared setup...
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      03-18-2011, 12:29 PM   #129
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Quote:
Originally Posted by cmark8 View Post
I just wished the moupe had more clearance up front... I would love to run an 18x9.5 et22 squared setup...
I was going to try and fit my 19x9.5 +43 LE37's up front to square out my setup more for track, but the LE's ended up selling =P
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      03-25-2011, 07:42 PM   #130
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2006 Z4M Roadster  [10.00]
2003 Z4  [5.00]
For a stock Z4MR would:
F 18 x 8.5 ET35
R 18 x 9.5 ET25
Tires:
F 235/40/18
R 265/35/18 work and look good?

Last edited by Samjam927; 03-26-2011 at 10:39 PM..
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      03-27-2011, 09:51 AM   #131
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BMW Z4 BBS wheels

I changed my wheels yesterday, and I cannot do in photo what we see in true.
Its awsome.

Front 225/40/18 8.5J ET 35 Rear 255/35/18 10J ET 35 no problems with space inside outside etc .. all perfect.

here some pict of my car...









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      03-27-2011, 06:46 PM   #132
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Quote:
Originally Posted by Samjam927 View Post
For a stock Z4MR would:
F 18 x 8.5 ET35
R 18 x 9.5 ET25
Tires:
F 235/40/18
R 265/35/18 work and look good?
BUMP! any help would be greatly appreciated
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