What Are Tires Made of?

tire stack

You may not often think about it, but that black ring around the wheel of your car contains much more than just plain rubber.

Tires are made up of a complex blend of different rubbers – natural and synthetic – plus a whole list of other construction materials. On average, a modern passenger car tire will contain up to 25 components and as many as 12 different rubber compounds. It all starts with natural rubber extracted from special trees grown in large plantations. This liquid (latex) coagulates with acid, is cleaned with water and pressed into blocks.

Synthetic rubber, meanwhile, is created in a separate process using a mix of chemicals in the laboratory. During the manufacturing stage, blocks (both natural and synthetic) are cut up, weighed and mixed with other ingredients.

Reinforcing Thread
The textile industry supplies base materials (rayon, nylon, polyester and aramid fibers) for the production of cords which serve as a reinforcing material within the tire. 

Steel for Strength
The steel industry supplies high-strength steel. This serves as the raw material for the production of steel belts (steel cord) and bead cores (steel wire) within the tire.

Material for Every Component
We can break a tire down into its components to see where each material comes in. Let’s start at the road surface and work our way inwards.

  • Tread – natural and synthetic rubber
    • Tire tread connects with the road and the sidewall, and has three areas:
      • Cap: This is the part of your tire that’s most in contact with the road. It provides grip on all road surfaces, wear-resistance and directional stability.
      • Base: Underneath the cap, the base reduces rolling resistance and damage to the tire’s internal structure – the casing.
      • Shoulder: At the outer edges of the tread, this area forms an optimal transition from the tread to the sidewall of the tire.
  • Jointless cap plies – nylon, embedded in rubber
    • This layer, which sits directly below the tread, enables travel at high speeds. Imagine gathering a length of twine back into a ball, coiling it around and around. Jointless cap plies are a little like this. They consist of a single, strong cord of nylon, embedded in rubber. This cord spirals around the circumference of the tire, from one side to the other, without overlapping.
  • Steel cord for belt plies – high-strength steel cords
    • Enhances shape retention and directional stability
    • Reduces rolling resistance
    • Increases your tire’s mileage performance.
  • Textile cord ply – rubberized rayon or polyester
    • This layer of textile controls the internal pressure of the tire and maintains its shape.
  • Inner liner – butyl rubber
    • Seals the air-filled inner chamber, controlling tire pressure
    • Acts as an inner tube in today’s modern, tubeless car tires
  • Sidewall – natural rubber
    • Protects the casing from external damage and atmospheric conditions
  • Bead reinforcement – nylon or aramid
    • Enhances directional stability
  • Bead apex – synthetic rubber
    • Performs the same tasks as the bead reinforcement while also providing additional steering comfort
  • Bead core – steel wire embedded in rubber
    • Ensures that the tire sits firmly on the wheel rim.