Maybe....Maybe not......I found this while watching the video posted by GM on a prototype for SEMA...
It say's wheel size 20 x 10
and 20 x 11 via Z/28 blanks
...check what's written under suspension in the video.
Zoom in at 2:03
of the video below:
UPDATED 11-11-2010: Tire size up front is 285/30 R20 and rears are 295/35 R20