Tire construction has evolved over the last century, from covering a wooden wheel with a thin coat of rubber to becoming an engineering marvel.

All tire manufacturers choose specific materials and components with their own technology in mind. They design each tire component to provide benefits specifically related to its function, while working together with all other components.

Most of the components that go into making a tire are hidden from view, but are essential to creating a tire that supports the weight of today's vehicles and their contents.

Most tires consist of the following components:

• Beads
  The beads consist of monofilament steel cords wound together to form a cable, then coated with a rubber compound to withstand the rigors of mounting and chafing. The beads strengthen the tire, and secure it to the wheel rim at its inside edges.
  
  
• Toe Guard
  The toe guard protects the bead assembly when a tire is mounted or dismounted.
  
  
• Apex
  The apex is a rubber component that adds support between the beads and body ply, and provides transition to the sidewall.
  
  
• Chafer
  The chafer protects the beads where the tire touches the wheel, and protects the body ply from chafing against the rim flange.
  
  
• Body Ply (Plies)
  The body ply consists of steel or layers of fabrics, such as polyester cord. In radial tires, the polyester cords run perpendicular to the tread, while the cords in many older tires run diagonally. The body ply is coated with rubber to improve the bond with other components, and to provide structural integrity to the tire.
  
  
• Wedge
  The wedge is a rubber insert positioned between the body ply and belts, providing stiffness at the belt edge. It also keeps the tread level and flat for better contact with road surfaces.
  
  
• Belt System
  The belt system provides dimensional and tread stability, and protects against punctures to the tread area. The most common belt material is steel, which provides strength and stability to the tread area without adding a lot of weight to the tire.
  
  
• Overlay
  The overlay stabilizes the belt system, and increases tire durability and high-speed capacities.
  
  
• Liner
  The liner is a rubber compound that seals air in the tire, much like an inner tube.
  
  
• Sidewalls
  The sidewalls provide lateral stability, protecting the body ply and preventing air from escaping. Special rubber compounds are added for flexibility and weather resistance. Manufacturers that produce high-end performance tires may also incorporate steel or nylon inserts to provide quicker steering response.
  
  
• Tread
  The tread contributes to the effectiveness of wear, handling, and traction. The tread consists of rubber compounds from various types of natural and synthetic rubbers that provide the traction between the tire and road surfaces.
  
  
• Cushion Gum
  Many higher-performance tires include an extruded component between the belt system and the tread to separate the tread from mechanical wear.
  
  

To guarantee quality and efficiency, the tire components are assembled using automated tire machines. Typically, the basic process includes the following two stages:

After the tire is assembled, it is processed in a curing machine that uses heat to bond the components, and to mold the markings and tread patterns. For the final step, the tire must pass a rigorous inspection test, which includes uniformity, durability, and visual considerations. For commercial tires, X-ray machines are used to inspect the steel core structure.