Z4C and Z4MC wheel offsets

[Mike-]

Hey

Wonder if anyone can help. Are there any differences in what wheel a standard Si can take vs an M? The body looks the same to me.

Also wondering if anyone has fit anywhere close to a 10” wheel at the back with ET22. Specifically the Strom STR2 wheel shown below in the eBay link, which to me looks like the 10” version in the rear rather than the 9.5, does anyone know the owner so I can find out? Searched to see if the car was on here but no dice. Thanks.

https://www.ebay.co.uk/itm/264771187844 (This one)

 

[mr wilks]

10j et22 would work on a ZMC but not on a Si.
As a target with Si aim for et35-40 front & rear ideally with 8j% 8.5j F 9.5j/10j R.

 

[Mike-]

Where does the difference lie between the Si and the M? The hub? Rear quarters have the exact same part number.

I’ll aim for the 9.5 then which comes in a higher offset, still curious though.

 

[mr wilks]

Where does the difference lie between the Si and the M? The hub? Rear quarters have the exact same part number.

I’ll aim for the 9.5 then which comes in a higher offset, still curious though.

Factory wheels for Si are
8j et47
8.5j et50

For the M
8j et42
9j et30

 

[z4pilot]

Where does the difference lie between the Si and the M? The hub? Rear quarters have the exact same part number.

I’ll aim for the 9.5 then which comes in a higher offset, still curious though.

I think the rear axle widths are different, hence the different wheel offsets to maintain the overall width.

 

[Mike-]

Where does the difference lie between the Si and the M? The hub? Rear quarters have the exact same part number.

I’ll aim for the 9.5 then which comes in a higher offset, still curious though.

I think the rear axle widths are different, hence the different wheel offsets to maintain the overall width.

Righto, you’d think the M would be wider rather than narrower, odd one.

If anyone has a picture of a 10” wheel on a Z4C in whatever offset that would be useful.

 

[mmm-five]

Righto, you’d think the M would be wider rather than narrower, odd one.

The M is not narrower, it's the same width as the non-M.

It's just the offset is changed to take account of the wider track - otherwise the wheels might be outside the bodywork and require a whole new rear wing to fit...which was not likely to happen with the relatively small production run.

If you want to go really wide, then talk to Goke or BMW Motorsport and they'll be able to provide GT3 panels so you can fit mahoosive rears!

 

[Mike-]

Righto, you’d think the M would be wider rather than narrower, odd one.

The M is not narrower, it's the same width as the non-M.

It's just the offset is changed to take account of the wider track - otherwise the wheels might be outside the bodywork and require a whole new rear wing to fit...which was not likely to happen with the relatively small production run.

If you want to go really wide, then talk to Goke or BMW Motorsport and they'll be able to provide GT3 panels so you can fit mahoosive rears!

But a lower offset means they stick out more, if the clearance is kept the same between the tyre and arch for M and non M. Otherwise they have the same clearance and axel width, but with less arch to tyre space on the M. Honestly, I’m confusing myself at this point.

 

[StigJ]

I have 10x19 ET41 rears with 265/30 Michelin PS4S tires. Tried 3mm spacers and I had a tiny rub in the wheel arch. Without spacer the wheel touches the inner plastic on some occations.

 

[Raj_UK]

I’m pretty certain the Z4m / m3 rear axle is shorter. The low offset wheel compensates to bring the wheels outwards. The track maybe a few mm wider than the non m but not as much as the wheel offset would have you think.

 

[BMWZ4MC]

I have 10x19 ET41 rears with 265/30 Michelin PS4S tires. Tried 3mm spacers and I had a tiny rub in the wheel arch. Without spacer the wheel touches the inner plastic on some occations.

Your Zed looks great, as ever Stig

 

[StigJ]

Your Zed looks great, as ever Stig

Thanks

 

[Mike-]

I’m pretty certain the Z4m / m3 rear axle is shorter. The low offset wheel compensates to bring the wheels outwards. The track maybe a few mm wider than the non m but not as much as the wheel offset would have you think.

I have 10x19 ET41 rears with 265/30 Michelin PS4S tires. Tried 3mm spacers and I had a tiny rub in the wheel arch. Without spacer the wheel touches the inner plastic on some occations.

Cheers, this looks like a big fat no for an ET22 on a 10” then, looks like I’ll be going for the 9.5 with the higher offset.