Paul, One thing to watch out for with moon hubcaps is that they are chromed stainless steel, instead of chromed steel.
In some climates chromed steel may hold-up fine, but near the ocean or in the snowbelt where salt & chemicals are encountered, stainless is the way to go.
I had a set of steel ones and after 2 years I tossed them 'cause I couldn't get the rust and pits to buff out, even using steel wool.
Just a thought ('depends greatly on climate) as I live in the midwest and we have snow/ice which brings out the "salt-shaker" trucks.
MarkE