Wheel Offset Question - Please, Help!

[Rebank@xxxxxxx]

My E30 M3 is specked for ET20, I am told.  What will happen if I use wheels
with ET11?  BBS recommends spacers, while a guy at Tire Rack says that spacers
will reduce the offset.  I am thinking that if the offset is positive, spacers
will reduce it, and if it is negative, spacers will increase it.  Who is
right?  What will happen if I use wheels with ET11?
Thanks in advance.
Edward

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