Tire Anatomy

What’s inside a tire?tiresafety_inside_diagram

Modern tire technology blends a unique mix of chemistry, physics and engineering to give consumers a high degree of comfort, performance, efficiency, reliability and safety. Many tires are custom-designed to meet the stresses and performance needs specified by the maker of a particular model vehicle. Every tire is carefully inspected, and random samples are pulled for additional safety tests. As part of these tests, tires are x-rayed, cut apart and examined, run on test wheels, or road-tested to evaluate handling, mileage and traction performance. If properly cared for, tires can last a long time – usually from 40,000 to 80,000 miles, depending on the application.  Below we describe the parts of a tire:

TREAD:  The tread provides traction and cornering grip.  It is made from a mixture of many different kinds of natural and synthetic rubbers.

BELTS:  Belts made from steel are used to reinforce the area under the tread. These belts provide puncture resistance and help the tire stay flat so that it makes the best contact with the road.
SIDEWALL:  The sidewall provides lateral stability for the tire, protects the body plies and helps keep the air from escaping. It may contain additional components to help increase the lateral stability.  It protects the side of the tire from road and curb damage.

BODY PLY: The body is made up of several layers of different fabrics, called plies. The most common ply fabric is polyester cord.  The plies are coated with rubber to help them bond with the other components and to seal in the air. This is what gives the tire strength and flexibility.

BEAD: The bead is a loop of high-strength steel cable coated with rubber. It gives the tire the strength it needs to stay seated on the wheel rim and to handle the forces applied by tire mounting machines when the tires are installed on rims.  It is what assures an air-tight fit with the wheel.

INNERLINER: Responsible for keeping the air inside your tire and retaining the proper inflation pressure.