what are rims on a car

Rims are a component of a wheel, and they are not interchangeable with the term "wheel". The rim is the outer edge of the wheel, where the metal meets the rubber of the tire, and its the diameter of the rim thats measured to determine wheel size. The rim holds the tire in place and gives the entire wheel strength and support, and it also maintains an airtight seal with the tire. Rims are generally made of either steel or alloys of aluminum or magnesium, and they can be part of aftermarket or decorative wheels. The spokes and central wheel disc, which are also part of the wheel, are not part of rims.