will m5 rear wheels be further in than my stock 124?

and body have pics for comparison?
and what is the recommended depth?

 

The 166 rim with M5 offsets will be 6mm farther out than the 124 in the rear, but you can still use a 15mm spacer with the 275 tire for max push outward. The fronts will be pushed 14mm farther out than the 124's....perfect fitment.

 

i have stock M5 rims on my 545i and ran w/out spacers until last week when I put 10mm Rogue Engineering on.....looks way better. Go for it!

 

Yes, that is correct... per correction to my above post....10mm is the ideal spacer for the rear. I forgot they are ET28, not ET32 like my 172's.