Okay, there are now (at least) three places to buy flush hub caps:
Racing Disc Hubcaps (Pop-On). Scion Hubcaps, Vintage, Kustom Wheel Covers
https://www.mooneyesusa.com/Store/pr...09b62c95f03aa2
Full Moon Racing Disc Hubcaps, Stylish Look, Great Prices, AutoAmenity.com
Are there any functional differences? The first one (Hubcap Mike's) seems to be the least expensive, and some have a (mild) dome, and a (mild) step near the rim...
A related question: I recently had a valve stem fail in one of my alloy wheels. It leaked a ton of air as it moved from side to side. The garage that repaired it only had long stems, so it probably is whipping around more than the short one... Finally, my question: has anybody used the bolt in stems?