I'm also looking to swap the OEM 535i steering wheel for the european M-Tech II wheel. Anyone ever done this? The OEM wheel is nice but pretty large. I thought the M-Tech I wheel would be a little easier to handle, but the M-Tech II wheel is so much nicer (IMO).
Yes, it is a direct swap. Most of them are also the same size as the larger M-Tech I though, so no improvement there, but the grip is much nicer. I have one that is not currently in use, and am not letting go of it...
No, they are the same size if you are comparing large to large. There are smaller versions intended for the E30, but the larger versions are more common. They are all a direct swap if they have the same hub design. Like shifty said, avoid the later E34 and E36 units as they do NOT swap.
The 528e 4-spoke steering wheel is 400mm in diameter.
The 535i 3-spoke steering wheel is 385mm in diameter.
The M5 M-Tech I steering wheel is 385mm in diameter. Although some were available in 370mm diameter
The M-Tech II steering wheel is 370mm in diameter.