Help choosing spacers

[beemarman]

Hi,

You might be able to answer my question for me.

My current alloys is the original BMW 343M and I want to swap over to some aftermarket ones.

The car is a 2013 M6



The originals are

9.5x20 ET31 and 10.5x20 ET19
265/35/20 front and 295/30/20 Rear
The new ones

9x21 ET30 and 10.5x21 ET30
255/30/21 and 295/25/21

I was told I would need 15mm spacers for the front and 5mm for rears in order to get them to fit the BMW F13 M6.
Any ideas?

[carrera2RSL]

This is on an M6 right ? the 'originals ' are M6 spec

To fit at the same outside point as the originals you will need 5mm spacers front, I am sure 10mm will fit and will move the outer rim out by another 5mm if you want to run hubcebtric, atb the back you need 11mm to match, so 10mm will be fine, you might want to fit 15mm rear then you have added 5mm front and back if you run 10mm front and 15mm back. So 5mm front and 10mm back if you want to stay stock spacing

[carrera2RSL]

PS easy to work out a 9.5" wheel is 12mm wider than a 9.0" wheel, so for the same ET 6mm wider each side, the ET is negative offset meaning the centre of the wheel is inset to the car by that number so an ET30 is inset by 11mm more than a ET19, if the rim is wider or narrower then you need to adjust by that amount too. So at the front the 9mm is 6mm narrower each side and 1mm further out (30-31) hence a 5mm spacer will put the outer rim back in the same position

[beemarman]

Originally Posted by carrera2RSL

This is on an M6 right ? the 'originals ' are M6 spec

To fit at the same outside point as the originals you will need 5mm spacers front, I am sure 10mm will fit and will move the outer rim out by another 5mm if you want to run hubcebtric, atb the back you need 11mm to match, so 10mm will be fine, you might want to fit 15mm rear then you have added 5mm front and back if you run 10mm front and 15mm back. So 5mm front and 10mm back if you want to stay stock spacing

Hi,

Thanks. So I need 10mm front and 15mm rear?

[carrera2RSL]

I'd go for that if you want to have 5mm extra width at the front and back over stock I don't know M6 clearances but stock M5's can go 15mm extra over stock

[beemarman]

Originally Posted by carrera2RSL

I'd go for that if you want to have 5mm extra width at the front and back over stock I don't know M6 clearances but stock M5's can go 15mm extra over stock

Thank you very much. It's been very informative


Can you please just answer one more for me.


Same setup but the new alloys is ET25 front and ET25 Rear.

What spacer would I need for an aggressive setup?

Rear alloy size is 21x11 instead of 21X10.5

[carrera2RSL]

Not sure on what offsets the M6 can take so worth having a read then going the maths for your wheels, sorry