From an ePer version:
The spacer is part no. 60508888, listed the same for all stock 12V 164 cars, 2 for each car but the catalog doesn't specify front or rear. All of the 164s I've bought but for the one with aftermarket wheels have had these on the front, stock wheels and all, L and S. Just my experience.
The 5 holes in the spacer are for the lug bolts. The small remaining hole is for the protruding pin on the wheel, which holds the brake disc in place during assembly. It goes on the outside of the spacer, holding it on as well as the brake disc. Naturally, the lug bolts provide all of the in-use "hold-it-together" power, but you need something to keep things from shifting while you are mounting the wheel. Items 6&7 on the B/L figure and item 3 on the S wheel figure are wheel weights. I wondered and looked at the parts list, so I include that info for you, gentle reader.