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Discussion Starter #1 (Edited)


Occasionally I see threads asking for info on OE ZHP wheels.

I just installed my new wheels, so I had the chance to weigh and measure the factory wheels from my 2004 330Ci ZHP. Maybe this info will help reduce new posts by those folks that are bright enough to use Search.

FYI ***8211; at the time of this posting, my wheels are not for sale. I***8217;m just trying to share info.

2nd FYI ***8211; the measurements are made with a tape measure and straight edge. If you***8217;re looking for laser-tracking precision stats, they***8217;re not in this post. But for most purposes, these numbers should work. The weights are per a USPS scale, so they should be pretty accurate. :thumbsup:

OE Style 135 M Double Spoke ***8211; bolt pattern 5 x 120 mm

Front - 18x8
Overall Diameter 19.56***8221; (497 mm)
Overall Width 8.88***8221; (226 mm)
Backspacing 6.31***8221; (160 mm)
Offset 1.85***8221; (47 mm)
Weight 28.16 lb (12.77 kg)

Rear - 18x8.5
Overall Diameter 19.56***8221; (497 mm)
Overall Width 9.38***8221; (238 mm)
Backspacing 6.69***8221; (170 mm)
Offset 2.01***8221; (51 mm)
Weight 28.20 lb (12.79 kg)

If I figure out an accurate way of measuring the diameter and depth of the centerbore, I***8217;ll post a reply to this thread. But my mic is too wide to fit down inside the wheel and still expand to hit the sides of the bore.

I hope this helps answer some of the questions people have about these wheels.
 

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Great idea -

On the weight though, this site - http://felgenkatalog.auto-treff.com/ - lists it as 11.23kg and 11.93kg, which also corresponds to (and means it was probably taken from) the data in the TIS, which lists the weights as 11.226kg and 11.926kg.

While I'm sure you were very careful in your measurements, when I've tried to do similar measurements myself I've found a lot of variation can be introduced based on how the wheel sits on the scale. This might also explain the almost identical weight you found between the two wheels rather than the about 1.5 pound difference cited by other sources.
 

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Discussion Starter #3
Well, that's interesting. I used the same scale to measure my new wheels and they weighed out at almost the exact weights the mfg said they would be. And the scale noted the 1/2 lb difference between the front and the rear.

The OE wheels actually fit easily on the scale, and I just put a twist-tie on the scale (was too light to register on it's own) to keep them from rolling off without me having to touch them. It's possible the calibration of the scale was off, but that would mean my Forgelines are actually 2 to 3 lbs lighter than what the mfg said they would be. :hmm:

I suppose it's possible that there was a production change and the new 135Ms are lighter than the ones built in 2004 to go on my car. But that would be surprising if true.

If I have access to another scale anytime soon, I'll re-weigh them. If I come up with different weights, I'll add to this thread.
 

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Discussion Starter #5
That's not a dumb question at all.

Weights were removed. Rubber valve stems still installed, center caps in place. But no balancing weights.

:thumbsup:
 

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Holy old thread.

Front - 18x8

Backspacing 6.31" (160 mm)

Rear - 18x8.5

Backspacing 6.69" (170 mm)
The backspacing should be measured from the wheel mounting surface to the vertical centerline of the wheel (looks like you measured it to the inside edge of the wheel?). So I believe it should be a bit smaller than that.
 

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What makes these "M" wheels? Does "M" stand for "Moment of Inertia?" That's at least 8 pounds per wheel heavier than some of the good cast wheels out there in the same size. Jeez.

OE BMW wheels sure are nice looking, but damn, even the "sporting" ones are heavy. I figured maybe my 161's were a fluke because they were designed for run-flats and came on the base-model E90.
 

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Old thread I know, but thanks for weighing them! 28lb is insanely heavy for a "sport" wheel. Once I saw this thread I went out and got a set of 17" BBSes.
 

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What makes these "M" wheels? Does "M" stand for "Moment of Inertia?" That's at least 8 pounds per wheel heavier than some of the good cast wheels out there in the same size. Jeez.
:rofl: was wondering the same thing
 

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Discussion Starter #13
Holy old thread.



The backspacing should be measured from the wheel mounting surface to the vertical centerline of the wheel (looks like you measured it to the inside edge of the wheel?). So I believe it should be a bit smaller than that.
Sorry to respond to this 5 months late, didn't realize it had been bumped.

No, what you're referring to is offset. In that case, you're correct that it's the distance from the centerline of the wheel to the mounting face. Offset is almost always expressed in mm, and is positive if the mounting face is outboard (curb side) of the center, negative if the mounting face is inboard (brake side) of the center.

Backspacing is way easier to measure. The offset can be calculated by dividing the actual width of the wheel in half and subtracting the backspacing measurement.

Please see my original post, the offset is listed directly under the backspacing.

:thumbsup:
 

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Discussion Starter #16
What are the standard tyre size from front and rear wheels,
Ive read 225 fronts and 255 rears, is that correct?
OE tires are 225/40R18 and 255/35R18 Michelin Pilot Sports.
 

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So if I get new wheels to replace my 135Ms that shave, as an example from above, 8 pounds off a wheel, will that really translate into noticeable results? Better fuel economy? Faster acceleration times? Better handling? etc
 

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Discussion Starter #18
Results, yes. Noticeable, maybe not so much.

If there's one aspect I noticed after putting lighter wheels on my car, it was braking. Seemed to me that under heavy braking, the car stopped just a tiny bit better with the lighter wheels. Could also be one part of my brain convincing another part to feel a difference in order to justify the expense. LOL

Under highly controlled circumstances, you might be able to measure an mpg increase or better 0-60 or 1/4 mile or lap time. But real world driving varies so much that the difference the lighter wheels makes gets lost in the normal variance of such things.

$0.02
 
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