jgubser -
Welcome to EM! I love those snap-in racing disks, but there's an even bet they will fall off over time. I think it depends on how nice your roads are.
It should be the whole cap, but you can also go with "mostly smooth" covers that have vents on the side. Here's an old (late 1980's?!?!?) Honda style :
Honda Civic Hubcaps, Honda Civic Wheel Covers and hub caps - Hubcaps.com
CarloSW2