Tread Breakers Buff line cushion Tread reinforcing ply Inner liner Caroass plies Apex strip Wire beads Bead heel Bead toe Sidewalls Chafers Flippers Ply turn ups Carcass Plies or  Casing Plies Figure 13-130.  Construction nomenclature of an aircraft tire. Bead  Carcass Plies Tread 13-78 The tire bead is an important part of an aircraft tire. It anchors  the tire carcass and provides a dimensioned, firm mounting  surface for the tire on the wheel rim. Tire beads are strong.  They are typically made from high-strength carbon steel wire  bundles encased in rubber. One, two, or three bead bundles  may be found on each side of the tire depending on its size  and the load it is designed to handle. Radial tires have a single  bead bundle on each side of the tire. The bead transfers the  impact loads and deflection forces to the wheel rim. The  bead toe is closest to the tire centerline and the bead heel fit  against the flange of the wheel rim. An apex strip is additional rubber formed around the bead  to give a contour for anchoring the ply turn-ups. Layers  of fabric and rubber called flippers are placed around the  beads to insulate the carcass from the beads and improve tire  durability. Chafers are also used in this area. Chafer strips  made of fabric or rubber are laid over the outer carcass plies  after the plies are wrapped around the beads. The chafers  protect the carcass from damage during mounting and  demounting of the tire. They also help reduce the effects of  wear and chafing between the wheel rim and the tire bead  especially during dynamic operations. Carcass plies, or casing plies as they are sometimes called,  are used to form the tire. Each ply consists of fabric, usually  The tread is the crown area of the tire designed to come in  contact with the ground. It is a rubber compound formulated to  resist wear, abrasion, cutting, and cracking. It also is made to  resist heat build-up. Most modern aircraft tire tread is formed  with circumferential grooves that create tire ribs. The grooves  provide cooling and help channel water from under the tire  Once the plies are in place, bias tires and radial tires each  have their own type of protective layers on top of the plies  but under the tread of the running surface of the tire. On bias  tires, these single or multiple layers of nylon and rubbers are  called tread reinforcing plies. On radial tires, an undertread  and a protector ply do the same job. These additional plies  stabilize and strengthen the crown area of the tire. They  reduce tread distortion under load and increase stability of  the tire at high speeds. The reinforcing plies and protector  plies also help resist puncture and cutting while protecting  the carcass body of the tire. nylon, sandwiched between two layers of rubber. The plies  are applied in layers to give the tire strength and form the  carcass body of the tire. The ends of each ply are anchored  by wrapping them around the bead on both sides of the tire  to form the ply turn-ups. As mentioned, the angle of the  fiber in the ply is manipulated to create a bias tire or radial  tire as desired. Typically, radial tires require fewer plies  than bias tires. 