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..._Specifications
I'd just never seen a Zed with different diameter front/rear wheels before? i know it's normal on Honda NSX's and Lambo's etc
Yeah I thought it was a bit weird, but its "Track 18/19" v.2" on here, http://www.350z-tech..._18.2F19.22_v.2 looks like its not like hes fobbing me off with a franken-set
Cool, you got yourself a real bargain and will have a pretty unique setup bud