I have a set of used BC forged BX05 concave forged wheels that are specifically made for a late model M6.
Specs:
21x9.5 ET21 295/20/21 accelera PHI tires with 3/32 tread
21x11 ET5 255/30/21 Pirelli p-zero tires with 4/32 tread
TPMS sensors are not included.
the tires don't have much tread and probably need to be replaced in 3k-5k miles.
http://www.pyspeed.com/BC-Forged-Whe...-p/bc-bx05.htm
http://www.6post.com/forums/showthread.php?t=912153