Most people think of tires as simple technologies—some rubber poured into a mold. And to be honest, tires do seem pretty simple when compared to the jumble of metal under your hood. Tires suffer from under-appreciation because most of their technology is always hidden from view, buried under a thick layer of vulcanized rubber.
To get an idea of the anatomy of a tire, the average car tire is built from over 200 materials converted into various rubbers, plastics, metals, and fabrics.
Inner tube
The first layer of a tire, starting on the inside, is a thin, air-tight sheet of synthetic rubber. This forms the inner tube. A good inner tube will help maintain your tire pressure which will increase the life of your tire and the gas mileage of the car.
Casing
The second layer consists of parallel fabric/metal cords called casings which provide the substructure for the tire. The careful orientation of these cords help to prevent the rubber from stretching or breaking. When a company designs a new tire, a lot of energy goes into the placement, angles, and materials used in these casings. The strength and longevity of your tire is due to this part of the tire—a part you are never really meant to see.
Beads
A tire also has steel rope around the inside parameters that are designed to fasten it to the rim of your wheel. This steel rope is secured by the casings and eventually melted into the rubber itself.
Rubbers
Two top layers of the tire we actually see. These consist of various rubbers—each carefully selected and designed for particular functions—strength, flexibility, traction, toughness, etc. These layers reinforce the side wall of the tires and a final layer is added to the parameter that will eventually be formed into the tread (the tread pattern itself is carefully designed to whisk away water and provide stability and traction at high speeds). Just as the casings strengthen the rubber, the rubber also helps insulate the casings so that they stay cool enough to maintain their integrity.
Finishing
While the tire is being shaped and cured, the various materials bond together, creating the finished product—a fairly unimpressive-looking black donut. But lift a quality tire, and you can tell (simply by its weight) that there’s a lot going on inside. Lift a cheap tire with your other hand, and you’ll begin to understand.
