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      11-07-2007, 05:51 PM   #23
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Even if fine, forged 19s have the very same mass with "normal" 18s, this mass is spread around a circle of bigger radius than than the one of the 18s, causing more rotational inertia and thus impeding [more than 18s] acceleration and deceleration.
When it comes to brakes, 18s can house brake discs up to 360mm diameter (14 inches +). Really fine, sophisticated brakes of that diameter are capable of stopping anything, forever.

The question is why BMW had to make these M3-specific 18s so ugly.
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      11-09-2007, 04:09 AM   #24
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cast

Greg, many thanks for the info. Today I found balancer weights attached on my wheels, which verifies your info.

I am not too excited about cast either and will change them to forged ones (BBS or Neez). I may go for 19' if good EDC-enabled suspension kits become avilable for lowering the height a bit.
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      11-09-2007, 01:18 PM   #25
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Springs

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... if good EDC-enabled suspension kits become avilable for lowering the height a bit.
EDC does not require special springs. A spring is a spring is a spring. Some folks may tell you it requires them but they are simply lying. There is no way to change the shocks though with EDC.
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      11-09-2007, 06:18 PM   #26
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EDC does not require special springs. A spring is a spring is a spring. Some folks may tell you it requires them but they are simply lying. There is no way to change the shocks though with EDC.
They may be "special" in that they must be sized correctly for the EDC setup, which may well have different springs than the base one.
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      11-09-2007, 09:48 PM   #27
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Quote:
Originally Posted by Coyot View Post
Even if fine, forged 19s have the very same mass with "normal" 18s, this mass is spread around a circle of bigger radius than than the one of the 18s, causing more rotational inertia and thus impeding [more than 18s] acceleration and deceleration.
When it comes to brakes, 18s can house brake discs up to 360mm diameter (14 inches +). Really fine, sophisticated brakes of that diameter are capable of stopping anything, forever.

The question is why BMW had to make these M3-specific 18s so ugly.
I agree that tje 18's are fugly. In the e46 M3 did BMW change the wheel design at some point or were the same wheels offered throughout the the entire model life
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      11-10-2007, 12:38 PM   #28
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I've owned an E46 M3 with OEM 18" wheels. The new E92 M3 is a different design and less attractive than the E46 OEM 18" wheels.

When I purchase my E92 M3, I'll opt for the 19".
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      11-18-2007, 09:07 AM   #29
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I'm definitely leaning toward 19". Just out of curiosity, is anyone aware of any quantified difference in acceleration (or other quantifiable differences in performance) between either the E46 or E92 M3's with 18" vs. 19" wheels? It is quite understandable that with all other factors being equal, the 18's would be better in certain respects, but how much better (would it be 0.1 to 0.2 seconds for 0-60 or quarter-mile? More or less?) If the 19" forged for the E92 are the same weight as the cast 18's, it would seem (based on the comments above) that any acceleration advantage of the 18's would be very slight... Thanks.
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      11-20-2007, 08:18 AM   #30
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Quote:
Originally Posted by Coyot View Post
Even if fine, forged 19s have the very same mass with "normal" 18s, this mass is spread around a circle of bigger radius than than the one of the 18s, causing more rotational inertia and thus impeding [more than 18s] acceleration and deceleration.
When it comes to brakes, 18s can house brake discs up to 360mm diameter (14 inches +). Really fine, sophisticated brakes of that diameter are capable of stopping anything, forever.

The question is why BMW had to make these M3-specific 18s so ugly.
If both rims were without tires mounted I would agree with that statement. However, they do have tires mounted...

If the E46 wheel selection was any indication, the forged 19" wheels of the E92 M3 will be lighter than the 18" cast wheels. This and the same weight or even lighter 19" tires (less sidewall but wider, probably slightly different compound) will make any difference in acceleration from the 18" wheels/tire combo insignificant. Done right (suspension designed for 19") and the difference in ride should be negligible. The difference in handling however, should be superior due to the stiffer sidewalls.

That's exactly the same concept used for the CSL: lighter wheels (although not forged but spun cast) and lighter tires than the OEM 18 wheel/tire combo.
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      11-20-2007, 04:19 PM   #31
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Technic:
Yours is a serious contribution to this discussion and I appreciate it.
We will find out which of us is (marginally) right only if we get specific data.

I think most people would opt for a beautiful, classic and classy, 18" rim design, cost taken into account.
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      11-21-2007, 02:42 AM   #32
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Quote:
Originally Posted by GregW / Oregon View Post
They may be "special" in that they must be sized correctly for the EDC setup, which may well have different springs than the base one.
Perhaps splitting hairs but if they don't fit, they don't fit. Even if the EDC shocks are a different size than non EDC shocks the springs for the EDC system are not "special". What I meant is that a spring has a size, rate and travel and that is about it, you can't "tune" a spring in some mystical/magical way to match EDC.
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      11-27-2007, 12:37 PM   #33
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When I bought my 330i I was told to get the 17" instead of the 18" sport package because the pot holes here in NYC would destroy the 18" wheels.

Is this anywhere close to true? There are some massive bumps that will really rock the car, but will they dent the wheel?

Would the forged 19" actually be stronger than the cast 18" for city driving?

I don't know how this car would survive in NYC....
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      11-27-2007, 06:23 PM   #34
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On my 330ci I've had 3 different sets of wheels on it while I've been in Albany. My nice set I've kept off for fear of it denting from all the bumps but while I had them on it didn't seem to hurt it too bad. I have the default rims that I bought the car with on it now. No noticeable dings or dents there either. The third pair I've had on the car are steel-wheel rims for winter tires. I've had those on an extended amount of time to save on shipping costs since I store my wheels at my house in Texas. The steel wheels have dented, dinged, and at one point in time almost became square. I had to have the dealership hammer it back circular. So it is definately possible for potholes to hurt and ruin a set of rims but most high quality rims are considerably stronger than steel wheels. So I'm willing to bet you would be 'ok' with 18's. You just have to get use to a choppier ride.
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