Osteopath,
Try the search function on the site and you may find more information. An original steel wheel for your car is part number 40300-E4400 which is a 5-J x 14 size. 40300-E4600 is a 5-1/2 J x 14 optional wheel originally offered. They look like the pictures I have attached - black exterior / silver interior. Originally, the tire offered was a 175 SR-14 tubeless radial or a 175 HR-14. I'm currently not aware that this size is manufactured anymore, however 185 and 195 sizes are available and they fit fine. Wheels were encoded with a date of manufacture. If you are particularly nit-picky, you would want a wheel set date stamped prior to your month and year of manufacture, but once the hubcap is on, no one will be able to discern. I seriously doubt that Nissan has these wheels available so your search is probably going to include eBay and junk yards. Look out for rust. I had my sets refurbished several years ago for about $75 / wheel.