They make the wheel look pretty.
When your wheel is balanced it is attached to a balancing machine, a shaft sticks out of wheel balancing machine (where wheel is attached). The wheel is then installed onto balancing machine shaft via center of wheel (requiring removal of center cap).
Car lovers can find center caps for their Chrome Rims even if they are old. You can search websites like Ebay or Craiglist to see if anyone is selling spare parts for center caps or reach out to a dealer and ask for help.
Center caps were originally meant to keep dirt away from the spindle nut and wheel bearings. Now they are mainly a decorative way to hide the lugnuts.
The first place I would check is at your local junk yards. Most likely they will have them. If you can not find them there you can try hubcap heaven. They have just about everything for your rims there. If they don't you can try Amazon.com and they should be able to find some aftermarket center caps for you.
SOme 92 Caprice cars came with wheel covers other had aluminum rims.
Cheap center caps can be found at www.Hubcaps.com .
Try upstreamcentercaps.com if you want custom center caps. Otherwise you can find OEM center caps on ebay for a good price.
Amazon is a retailer that offers a good selection of center caps for automobiles. These include official center caps from a wide range of automobile companies.
Chevy center caps are basically hub caps. They go in the center of the wheel, giving the wheels a nicer look. The caps usually contain the Chevy symbol and/or name. The caps also protect the centers from dust and debris.
Wheel center caps are generally made of aluminum or chrome plastic.
The bst distributor of wheel center caps is CenterCaps.net: http://www.centercaps.net
You can find affordable wheel center caps on hubcaps-wheelcovers.com.
You're in luck, there are a few. The first is http://www.autoamenity.com/Center-Caps/Center-Caps.htm, whose specialty is chrome center caps. Next, there's http://www.centercaps.net/ and http://www.hubcaps.org/.