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Discussion Starter · #1 ·
It is commonly quoted as 74.1 mm

Just going to the thousandths, that could be anything from 74.051 to 74.199mm depending on whether they rounded off or truncated.

Don't know if this tiny gap will cause room temperature fitment issues but that might cause issues when the rates of contracting or expanding are different between the wheels and the centerpole leading to premature failure.


The reason I ask is because I might be looking at getting a set of rims that have a marginally smaller than 74.10 mm CB mounted onto my 01 M5.
 

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Wow, that's splitting hairs. I had some wheels rebored and I told the machine shop guy 74.1mm and they fit. He didn't ask for hundredths.
 
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Discussion Starter · #3 ·
Thanks! So this was really much ado about nothing!

I wonder if it would make a difference if these wheels are assigned to winter duty in Canada?

I was tempering my question with the knowledge that many cheaper aftermarket wheels for the tuner crowd are not even close to being hubcentric and even without centering rings, can sometimes endure many track days without fuss. But maybe that's because they weigh closer to 3000lbs as opposed to 4000lbs.
 

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I wasn't trying to belittle your question, but my guess would be hundredths and thousandths of a mm would be insignificant.
 

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Discussion Starter · #5 ·
There does exist a product that addresses my issue in certain circumstances.

Turner Motorsport - Item# 3075740725 - H&R 15mm Wheel Adapter Set To Fit E36/E46 Wheels To E39 5-series - E39

Unfortunately, these are not BMW fitment. They are also wide rims and I can't afford to push it out by 15mm as I don't feel like cutting / pulling fenders.


Actually now that I have searched further in google, I see that others have said it is actually 74.06mm so boring out to 74.1mm leaves a nice buffer.




If you had an E92 (whose CB is 72.56mm) and one bores out to the commonly quoted truncated 72.5... maybe one runs into issues?
 

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I see your concern but honestly I don't think its anything to worry about. If its 74.1 it will work. Some replica wheels are quoted 74mm and they also fit.
 
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What wheels are you thinking? :)
 

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Don't know if this tiny gap will cause room temperature fitment issues but that might cause issues when the rates of contracting or expanding are different between the wheels and the centerpole leading to premature failure.
Unless you store your car in a freezer box and drive it right out into d3ath Valley during the middle of summer, I highly doubt this will ever be of any issue to you or anyone else
 

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Discussion Starter · #10 ·
What wheels are you thinking? :)


Why? ;)

If it's cool, I would like to keep it under wraps until I get the chance to show everyone in the gallery. Won't be to everyone's liking anyway. Heck, I'm not even sure it will work since I don't have coilovers, camber plates, various sized spacers to help adjust. Also will likely have to get the fenders rolled aggressively or as flat as can be.

I may reach out for fitting tips in the months to come. (ie. Hey! Did you know GC coilovers will give you an extra 3mm of clearance on the inside?!) If it doesn't sound like I'm convinced I'm doing this, it's because I'm not.

I really do like the stock rims but I'd like to keep them in pristine condition.
 
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