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Discussion Starter · #1 · (Edited)
I am having a hard time finding a good selection of aftermarket wheels for the MZ4C. I would like to go with a 19" or possibly 20". I have been told the following on the 19" rim: Fronts can be 19 x 8.5 245/35/19 (offset 38-43) rears 19 x 9.5 275/30/19 (offset 18-25). Is this information accurate? Also if I go with 19" I would lower the car with the H&R springs.

Now for the biggie. If I was to go with a 20" rim what width of rim can I go with front and rear and offset of each as well as tire specs.

If a search is done at www.tirerack.com they do show a number of "compatible" 20" rims.

Here are the specs:

Size Selected: 20x8.5 Front
Recommended Tire Size: 255/30-20
Wheel Offset: 35mm

Size Selected: 20x10 Rear
Recommended Tire Size: 295/25-20
Wheel Offset: 25mm

Would these actually fit a MZ4C with stock springs or with H&R. With stock springs would the wheel gap be filled in a bit more than with 19" rims?

Here is another 20" spec option:

Size Selected: 20x8.5 Front
Recommended Tire Size: 255/30-20
Wheel Offset: 34mm

Size Selected: 20x10 Rear
Recommended Tire Size: 295/25-20
Wheel Offset: 20mm

Which set of these rims would actually fit with no rubbing with stock springs or H&R?
 

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Here's the scoop on my set up....

I'm on H&R springs
Volk Progressiv ME specs on my M Roady are; (same as M coupe)
Fronts = 19x8.5 ET35 with 245/35 PS2
Rear = 19x9.5 ET22 with 275/30 PS2

These clear with no rubbing, but are very close to the limit.

A couple of pics....


 

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Banned
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Discussion Starter · #5 ·
Here's the scoop on my set up....

I'm on H&R springs
Volk Progressiv ME specs on my M Roady are; (same as M coupe)
Fronts = 19x8.5 ET35 with 245/35 PS2
Rear = 19x9.5 ET22 with 275/30 PS2

These clear with no rubbing, but are very close to the limit.

A couple of pics....


Did you have the spring pads installed in the rear as well?
 

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295/25 - 20 is a WIDE rear tire. That's like porche territory right there. I wouldn't doubt that you may encouter rubbing issues with that, unless somebody can attest otherwise. I think 275 would be the max width you would want for rears, but not sure if that would be suitable for 20s.
 

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Oops... sorry I forgot that...... Yes. :thumbup:
-I must have missed something. What are spring pads and what do they do? Are they like bump stops?

Regarding the wheel/tire size question:
Don't put 20s on a Z4 M :soapbox:

But either way, it's not rim width that is as critical with regard to rubbing as tire width. You can easily run a 10" rear wheel on the Z4 M, maybe even an 11" - BUT you won't fit anything larger than a 275 back there without bodywork. So depending on your wheel width, the tire will just stretch more or less. This will of course affect your ride and handling - similar to stiffening the rear springs a little only the stiffness won't be modulated by your dampers.

245/275s seem to work fine for most everyone. There's no reason to think they won't also work with 20s if you get an appropriate aspect ratio. But be warned that all tires are NOT the same size even if they are listed that way! The 247/275 RA-1s I have on my M are a little wider than the same size PS2s (I think) and can rub a little if I hit a big enough bump. Even some PS2s ("MO" version specifically) can be different in diameter and/or width than other PS2s. So once you find the "right" tire, make sure you get the true tire width and diameter so you don't end up with any nasty surprises.
 
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