Wheel centerbore wire question

[eljssp8@aol.com]

Hi:
 
I have the SSR Competition wheels. While changing tires, I noticed at the outer 
edge of the centerbore, there is this thin wire shaped like a circle that is 
clipped right at the edge. This thin wire would be right up against the hub 
once the wheel is put on the car.
 
What is the function of this wire? I notice that I have one wheel without this 
wire, how critical is it that I get it replaced?
 
TIA,
Eric Cheung