The outer, often curved or circular, edge of something. (Cambridge Dictionary)
The outer often curved or circular edge or border of something. (Merriam – Webster)
The upper or outer edge of an object, typically something circular or approximately circular. (Oxford Dictionaries)
The rim of a container such as a cup or glass is the edge that goes all the way round the top. (Collins Dictionary)
Wheel / rim parts what is the difference between a wheel and a rim.
Staggered Wheels and Staggered Rims Explained – TSW Wheels.