I have been researching these wheels to find the correct sizes and offsets for the s2k. I recently spoke to one of the owners and this is basically what he said:

for the fronts, if you run 17 x 7.5, you will need a +35 offset (because of caliper clearance)---the +35 is still being tested and should be available in a few weeks

the 17 x 8.5 for the rear comes in a nice +50 offset

the wheel is also available in 18 x 8 all around with a +48 offset, which he claims s2k guys have been running; and an 18 x 8.5 with +48 is also available

now heres the best news: the wheel will soon be offered in 18 x 9 with the proper offsets for the s2k. so an 18 x 8 front and 18 x 9 rear will be nice.

check out these links:

http://www.rotawheels.com/products.php?id=66

http://www.machiii.net/wheels/D-2.html

the wheels look nice!