....and they do not have the plastic cup that fits on the back of each wheel behind the yellow center cap....according to the parts book.... Why's that?
You should also have a nominal 6" diameter rubber ring gasket that goes on the back side of the wheels as well (I have some good used extra sets for sale if you need them). This seals out any moisture from getting in from the back by compressing itself against the rotor when the wheels are torqued. The lug bolts torqued into their inserts will block moisture there. That leaves the center cap. They are not absolutely leak proof. So, Ferrari decided to put a secondary seal behind the center cap as a sort of "belts and suspenders" way to ensure no moisture could get in that way either. I don't use them. I doubt if many do The amount of moisture that could get in through the center caps is minimal and even if it does get in, there's not really that much consequence. Just to be sure, apply a small amount of anti seize around the rotor center flange before you put the wheels on. This will stop possible corrosion that can make it hard to break a wheel loose and get off again if enough moisture should ever get in.
