The days of tubed tires are over. Today's modern tires utilize synthetic rubber instead—specifically butyl rubber*—which is virtually impenetrable to water and air. However, over time, there will be slight air loss, so check your pressure every month.
Crown plies provide the rigid base for the tread.
The tread provides traction and cornering grip for the tire and is designed to resist wear, abrasion and heat.
The carcass ply is the layer above the inner liner and consists of thin textile fiber cords (or cables) bonded into the rubber. These cables are largely responsible for determining the strength of the tire.
The beads clamp firmly against the tire's rim to ensure an airtight fit and keep the tire properly seated on the rim.
The sidewall protects the side of the tire from impacts with curbs and the road. This is where the important details about the tire can be found, such as tire width and speed rating.