Nissan went to a "mag style" lug nut design on the new Z so you need to make sure whichever aftermarket lug nut you purchase is using this design. There not very common but you can find them some times. Toyota and Mitsubishi both use this same style lug nut as well as Jaguar and Land Rover but all in different thread pitches (1.5mm for Toyo/Mitsu/Jag) and diameter (14mm LR)
Most aftermarket lugnuts for a Nissan are 12x1.25mm conical/cone (60 degree cone shape) like this pic:
You want 12x1.25mm MAG style (flat washer style) like this pic:
