http://style77.com/products/advan-gt
I would think they are in the high 20lb each.
Other Forged wheels would be in the low to mid 20 lbs range.
Ask your vendor if the Advan GT's spec will fit with the orig stock spec below
For reference, the M5 stock comes in:
Front wheels: 20 x 9.5" ET31
Rear wheels: 20 x 10" ET19