Tires are a sophisticated mix of materials, including high-tech fabrics, natural and synthetic rubbers and even steel.
Running along the inner edges of a tire are the beads. Beads are high-strength steel, coated in rubber, which gives tires strength while also helping to hold the tire to the wheel. The body of the tire is actually made up of fabric, not rubber. The body is built from layers of fabric (each layer is called a ply). The plies aren't your run-of-the-mill cotton fabric; they're usually a strong composite material. The plies are coated with rubber, not only to help them hold air inside, but also to help them bond to the other parts of the tire.
For steel-belted radial tires, on top of the body are steel belts. These belts help make the tire relatively immune to punctures (since most nails and other road hazards aren't getting through steel) and they also help keep the tire tread, which is actually making contact with the road, at the optimum level of flatness. Keeping the tread's shape just right ensures more road contact, which means more traction and control.
Up to now we've only talked about how tires are built from bottom to top. But the sides of a tire are also important. The sides of a tire are called its sidewalls. It's here that information about the tire is printed and some tires have even have white or red sidewalls, just because they look cool. But, aside from looking good and providing information, the sidewalls help hold the parts of a tire in place and give the tire stability during side-to-side movements.
The final part of the tire is the tread. The tread is on the outer edge of the tire. Like the sidewall, it's made of a mixture of natural and synthetic rubber. Whereas the sidewall is relatively smooth, however, the tread has a series of grooves in it. Each grove serves to maximize performance and safety, whether a tire sports deep grooves for going off-road or just a few shallow grooves for hitting the track.
Now that you know what goes into a tire, keep reading to find out how it's all put together.