M Parallel fitment question

[hughesj]

I just got a 91 850i with style 9 turbines on it and I want to fit the style 37s from my e38. I took both cars to my local tire shop and gave him the tire sizes i found online to make the swap work, but then he proceeded to try to fit one of the front 37s to the e31 with the 235/50/18 tire on it. then he turns to me and says it won't fit because it's hitting the strut tower. I told him that i'm aware the tire won't fit and will instead need 245/40/18 tires mounted in the front instead, but then he started insisting that the wheel itself will hit the strut as well.

I started googling specs and found the following:

Style 9:
-Offset: ET15 | Width: 7.5"

Style 37:
-Offset: ET13 | Width: 8"

So if I'm doing math right here, that would mean that the internal edge of the wheel would be .25" - 2mm (roughly 4mm) closer to the strut than the style 9s, but that doesn't seem to be enough for them to come into contact.

Am I missing something here? i've seen 37s on e31s all over the internet. Are spacers needed to make the swap work? or does the guy just not know what he's talking about? (there was a little bit of a language barrier so it was had to understand him at times)

[rjbaren]

I have a set of Style 37s on my 95 840. I was advised to go square even though it looks cooler to have a staggered set. Anyway, I have 235 40 18s all around, no spacers, no rings, no shims, same lug nuts even.

[CD05001CIA]

- - - Updated - - -

You can try camber plates on the front to move the McPherson strut inward. The original fixed ones NOT the adjustable ones.

http://www.mwrench.com/download/cplateinstall.pdf

[bmwm42]

I have a staggered set on mine currently not with the car but have no issues

[Timm]

235/50/18 is the wrong size - for a 235 width you need a 40 aspect ratio - all explained here (with a table of acceptable tyre sizes):

https://www.meeknet.co.uk/e31/Timms_..._tyre_page.htm

235/40/18 and 265/35/18 are perfect for M-Pars. Make absolutely sure they are M-Pars, there are an amazing amount of replicas, the giveaway is that the hub bore on a replica is usually 74.1mm whereas the original is 72.6mm

[bmwm42]

235/50/18 is the wrong size - for a 235 width you need a 40 aspect ratio - all explained here (with a table of acceptable tyre sizes):

https://www.meeknet.co.uk/e31/Timms_..._tyre_page.htm

235/40/18 and 265/35/18 are perfect for M-Pars. Make absolutely sure they are M-Pars, there are an amazing amount of replicas, the giveaway is that the hub bore on a replica is usually 74.1mm whereas the original is 72.6mm

those are the exact wheel sizes im currently running

[Auraraptor]

I’m running 245/40F 275/35R on my 18x8.5et12 18x9.5et14.5 without issue on my 8

[hughesj]

235/50/18 is the wrong size - for a 235 width you need a 40 aspect ratio - all explained here (with a table of acceptable tyre sizes):

https://www.meeknet.co.uk/e31/Timms_..._tyre_page.htm

235/40/18 and 265/35/18 are perfect for M-Pars. Make absolutely sure they are M-Pars, there are an amazing amount of replicas, the giveaway is that the hub bore on a replica is usually 74.1mm whereas the original is 72.6mm

Thanks Timm. I took it back to him earlier today and gave him the specs, he has the tires on order now.

I’m running 245/40F 275/35R on my 18x8.5et12 18x9.5et14.5 without issue on my 8

These are the numbers I gave him

[hughesj]

Success!

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[Auraraptor]

Looks great! Im sure it handles great too.

In hindsight I may have gone 285...the 275 can spin easily triggering DSC. The 285 would have slowed that notable given the taller diameter and greater grip. Still can't argue with how lively it is now!

[mr1173]

285s are nice... but my car did not like them

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[Auraraptor]

Interesting…what wheels / offset are you running?

[TedBobo]

Success!

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Looks great! Nice color on your 8er too. I lived in OC until 2020…worked in Irvine.

[hughesj]

Looks great! Nice color on your 8er too. I lived in OC until 2020…worked in Irvine.

Thanks! she's going in for some paint work soon. the front and rear bumpers are fading and the driver side rear quarter had a poorly done color match job done at some point

[toomann]

Sweet!

[04SSHD]

You need different tires, I took my Style 37's from my e38 and fit them on my e31. With the correct tires they fit perfectly.

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[olinjohnston]

Was this the car advertised in Huntington Beach recently?

[hughesj]

Was this the car advertised in Huntington Beach recently?

Doubt it, I bought it from a used lot up in San Jose and drove it home. Beautiful drive!

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[IJustDrive]

285/35x18 fit perfect. Even lowered a tad. Please excuse the dirty wheels.



Sent from my iPhone using Tapatalk

[Auraraptor]

Yes, I have run 285 rears too in the past without issue… that’s why I was wondering what the size/offset was of the wheels of the gentleman who was having rubbing issues

[MParallel]

I have a set of Style 37s on my 95 840. I was advised to go square even though it looks cooler to have a staggered set. Anyway, I have 235 40 18s all around, no spacers, no rings, no shims, same lug nuts even.

You could go square with your tires, but staggered with the rims.

[01BMWs]

I had to deal with a front flat in my '91 850 so I took the opportunity to try and fit my style 37 (without tire) from e38. I thought I had a front wheel, but it must have been a rear cuz the inner lip scraped against the strut.

[Auraraptor]

Yes the MParr/37 rears will hit the E31 front strut without a spacer.

Ballpark (from memory; you can always go lower but the upper end limit is usually… assuming common/standard tire sizes)
7.5ET15-22
8.0ET10-20
8.5ET10-15
9.0ET10-12
9.5ET5-?? Not sure upper limit using standard/not-stretched tire sizes

The E31 steering geometry was optimized for between ET10-15 from factory…. going too low can really screw up turn in and induce annoying tramlining due to the altered scrub radius.

Over the years I have run over a dozen combinations… The short version is stick with that range, ESPECIALLY If you run ultra aggressive performance tires. (unless you really know what you’re doing)

EDIT: you also don’t have to believe anything I say, just start with a standard offset wheel and compare the change in steering/handling with 5, 10, and 15mm hubcenteric spacers on your favorite road course. It was a fun bit of experimenting I did now over a decade and a half ago…

[01BMWs]

I appreciate the info! My 850 came with style 65s 18" already on the car. They might be aftermarket tho cuz I haven't cleaned the backs to find if they're originals. Anyways, they fit fine (albeit too much fender gap) with 245/40/18s. I'm contemplating either refinish these style 65s or find a new set of wheels. With a search tho, its hard to find wheels that I like with the correct offsets. Maybe with spacers?