There is something installed on the brake that's sticking out.
See pics:

My summer Nismo rims fit fine.
But my winter rim will not fit over it.
Can someone tell me what this thing is for?
Is it ok to unbolt it and reinstall it when the summer rims are swapped back on?
I don't have a clue that this thing is.

 

Unbolt it

 

its just there so you dont put the stock rears on the fronts since theyre staggered. it has no effect on performance or fitment of any kind. unbolt it

 

Guys, thanks a million for the input. I unbolted it and the rims went on just fine.