I didn' bring my car home... I changed mine more than 6 months ago, can't really remember how I put them together. if my memory is correct the ring should be put between the two barings to support the baring inner part, so you won't break the barings when you tight up your wheels.
The ring have two side... wider side is for the larger baring, narrow side is for the smaller baring.
Don't leave anyting they gave you, must be a purpose. Let me know if the ring doesn't fit in between, i will have a look at my car this Sat for you.
thank you C hing, i think u are right, but for me, after insert this circle, the dog done can;t pass through enough to let the pin to pass. But anyway, u are right, there must be some function for this stuff. Let me disassembly and make it again. Thank