Wheel size makes no difference to traction control, so long as your tyre profiles are in range.
I noticed these as there was a guy inquiring about them in the wanted section, doing a little digging though and even the 18's are heavier than rays, just over 21lbs.
http://www.350z-tech.com/wiki/index.php?title=Wheel_Specifications
Says expect to pay £900 or more.. Think I got a bargain.. Also with some tyres