Originally Posted by Jeffblue

i'm telling you , you have the best winter setup in terms of wheels for this car (the stock 18's) buy some snow tires and upgrade or put back on the summer tires in spring.

found these on craigslist if you wantto inquire

Perrelli SottoZero Winter Tires 245 45 18
Snow tires for infinity G37S sports coupt
350Z & G35 Winter setup (Rims & Tires)

these you could buy the 245/45/18's for 100 each and then get a second pair from tire rack for full price and make out ok $ wise
245 45 18 DUNLOP SP WINTER SPORT M3 96V

tire sizes you can go for on the stock 18's are 245/45/18 all around, or 245/45/18 in rear and 225/50/18 in front.