There is a strong market for used rims, particularly for popular vehicles. While many people sell their rims online, some dealerships or repair stores might be willing to purchase them as well.
Rims are fairly simple parts that contain no moving components, so they are relatively easy to inspect and test. They are built to last the life of the car, as a broken rim while driving is a safety hazard, so used rims are generally safe to use. However, sellers typically look for original manufacturer rims. People looking to sell third-party rims might have difficulty finding buyers, although specialty shops might be willing to pay for rims they can sell for a significant profit.