I was looking at this website about the teltale differences between cast and forged wheels:
http://www.devinder.com/misc/tstars/tstars.html
Forging is supposed to produce a stronger yet lighter wheel compared to casting... and so I was wondering exactly which e31 wheels are actually forged.
The throwing stars I suppose should be forged.
The M-parallels are forged
The BBS, split rims ???
The alpinas, I've read are all cast ??? Certainly I've seen many alpina rims with dents showing they must be a fairly soft alloy.