To see if you need them, all you need to do is jack up one corner and remove all the wheel nuts. Move the wheel around on the hub and see if it can move up down and or left or right. If it can move, it means it will not centre correctly as the big hole in the middle of the rim is larger than the spigot/flange on the hub.
In the short term, when you do the nuts back up, nip them all up finger tight at first, and then slowly work your way around a few times until they are fully tight. This will help centre the wheel better on the nut tapers until you get the correct rings fitted.
Then go to an allow wheel seller in your local area, remove the wheel again and put it on their desk! They should be able to provide you with the correct spigot rings.
