[NC M550 VADER]

I have been spending far too much time thinking about upgrading my '11 550i wheels -- the high end aftermarket 21s are out of my price range right now -- but I think I have come up with a great compromise. Just need confirmation that this will work.

I have always liked the 21" style 128s from the e65s, and though the style 311s are similar, they simply do not offer the concavity I am after. Unfortunately, however, the e65 128s only come in et24.

That said, the e65 9x21 et24 should work as a front wheel on an F10, right? Basically, if I understand offsets correctly, going from a stock front offset of et33, this would push the front wheel out 9mm, yes? (Unless a 9" wheel up front means that there is no room to push it out any farther from a standard et33?)

Assuming the et24s up front will work, that leaves the rears. It occured to me that the e70 x5 also offered style 128s in 21", albeit 10" up front and 11.5 in the rear.

So why can't I just source X5 fronts, which are 21x10 with offset of et40, and use them as my rear wheels on the f10?

Perhaps I will need spacers in the rear, but I am already running staggered OEM 19s et 44, so this shouldn't present a problem with the strut regardless, no?

I think the style 128s in 21" -- with a drop, a course -- will look amazing on the F10, so hopefully some of you can confirm if my plan will work.

Thank you!

[bake]

Your offset calculations are not taking into account the additional width of the 9” wheel versus the 8.5” wheel. With that said, I think the fronts sit just a tad outside of your fender as this setup will be 15mm further out than a stock 19x8.5 Et33 setup. The 21x10 ET40 should work fine for your rears. By my calculations you should not need any spacers and it will sit flush. The rear stance should be similar to your stock 351M wheels with a 18mm spacer (calculation is actually 17mm but nobody makes 17mm spacers). You can play with sizes and offsets here.

http://www.e90post.com/forums/forumdisplay.php?f=12

[NC M550 VADER]

Originally Posted by bake

Your offset calculations are not taking into account the additional width of the 9” wheel versus the 8.5” wheel. With that said, I think the fronts sit just a tad outside of your fender as this setup will be 15mm further out than a stock 19x8.5 Et33 setup. The 21x10 ET40 should work fine for your rears. By my calculations you should not need any spacers and it will sit flush. The rear stance should be similar to your stock 351M wheels with a 18mm spacer (calculation is actually 17mm but nobody makes 17mm spacers). You can play with sizes and offsets here.

http://www.e90post.com/forums/forumdisplay.php?f=12

Thanks Bake! This is extremely helpful. I am fairly optimistic this setup will work (the calculator gives me comfort). 15mm wider up front gives me some pause, though, because I am not a fan of having the wheel stick out farther than flush. It seems like it will be very close, though. (There is also some conflicting info on the e65 wheel being et22 or et24.)

[remmib]

Cool idea.
One thing though, the e70 has a 74.1mm center bore, while the F10 has 72.56mm center bore, so center rings are needed in the rear.

No spacers needed in the rear, ton of room on the strut side, and I bet even the 21x11.5 would clear the struts. But probably a tad too aggressive in the fender side.

[bake]

Remmib, good point on the center bore, I didn't even think about that. I love the idea though. These types of wheel setups are what modding is truly about if you are able to source the wheels and make it work. Good luck with your project!

Originally Posted by remmib

Cool idea.
One thing though, the e70 has a 74.1mm center bore, while the F10 has 72.56mm center bore, so center rings are needed in the rear.

No spacers needed in the rear, ton of room on the strut side, and I bet even the 21x11.5 would clear the struts. But probably a tad too aggressive in the fender side.

[NC M550 VADER]

Originally Posted by remmib

Cool idea.
One thing though, the e70 has a 74.1mm center bore, while the F10 has 72.56mm center bore, so center rings are needed in the rear.

No spacers needed in the rear, ton of room on the strut side, and I bet even the 21x11.5 would clear the struts. But probably a tad too aggressive in the fender side.

Ahh, the ol' hubcentric ring solution!

Thanks for pointing this out, an easily solved issue, thankfully.

[NC M550 VADER]

Another thing that I wondering about is the concavity of the 21x9 et24 versus the 21x9 et41. Images of the 128s on an X5 show deeper concavity on the 11.5 rears (obviously), but it is virtually impossible for me to compare the et24 fronts of the 3e65 versus the e70 versions. It would be an absolute non-starter if my "rears" ended up with less concavity than my fronts.

Legit concern?