A tire or tyre is a ring-shaped component that surrounds a wheel's rim to transfer a vehicle's load from the axle through the wheel to the ground and to provide traction on the surface over which the wheel travels. Most tires, such as those for automobiles and bicycles, are pneumatically inflated structures, providing a flexible cushion that absorbs shock as the tire rolls over rough features on the surface. Tires provide a footprint, called a contact patch, designed to match the vehicle's weight and the bearing on the surface that it rolls over by exerting a pressure that will avoid deforming the surface.
Assorted new automotive road tires, showing a variety of tread patterns.
Tractor tires have substantial ribs and voids for traction in soft terrain.
John Boyd Dunlop on a bicycle, c. 1915
Studded winter tire
The rim is the "outer edge of a wheel, holding the tire". It makes up the outer circular design of the wheel on which the inside edge of the tire is mounted on vehicles such as automobiles. For example, on a bicycle wheel the rim is a large hoop attached to the outer ends of the spokes of the wheel that holds the tire and tube. In cross-section, the rim is deep in the center and shallow at the outer edges, thus forming a "U" shape that supports the bead of the tire casing.
Cutaway diagram of a rim and tire from an ATV
Cross section of a bicycle rim
A wooden bicycle rim with tubular tire
Scratched rim on a one-piece alloy wheel. The black residue remains from where the tire was seated on the "safety profile" rim.