Aircraft tyres, tubeless or tube type, provide a cushion of air that helps absorb the shocks and roughness of landings and takeoffs: they support the weight of the aircraft while on the ground and provide the necessary traction for braking and stopping aircraft on landing. Thus, aircraft tyres must be carefully maintained to meet the rigorous demands of their basic job to accept a variety of static and dynamic stresses dependably—in a wide range of operating conditions.
Aircraft Tire Construction
Dissect an aircraft tyre and you'll find that it's one of the strongest and toughest pneumatic tyres made. It must withstand high speeds and very heavy static and dynamic loads. For example, the main gear tyres of a four-engine jet transport are required to withstand landing speeds up to 250 mph, as well as static and dynamic loads as high as 22 and 33 tons respectively..
The tread is made of rubber compound for toughness and durability, the tread is patterned in accordance with aircraft operational requirements. The circumferential ribbed pattern is widely used today because it provides good traction under widely varying runway conditions.
One or more layers of reinforced nylon cord fabric strengthens the tread for high speed operation. These are used mainly in case of high speed tyres.
These extra layers of reinforcing nylon cord fabric are placed under the tread rubber to protect casing plies and strengthen tread area. They are considered an integral part of the carcass construction.
Casing Plies/Cord Body
Diagonal layers of rubber-coated nylon cord fabric (running at opposite angles to one another) provide the strength of a tyre. Completely encompassing the tire body, the carcass plies are folded around the wire beads and back against the tyre sidewalls (the "ply turnups").
The beads are made of steel wires embedded in rubber and wrapped in fabric, the beads anchor the carcass plies and provide firm mounting surfaces on the wheel.
These layers of fabric and rubber insulate the carcass from the bead wires and improve the durability of the tyre.
The chafers are layers of fabric and rubber that protect the carcass from damage during mounting and demounting. They insulate the carcass from brake heat and provide a good seal against movement during dynamic operations.
The inner bead edge closest to the tyre center line.
The outer bead edge which fits against the wheel flange.
On tubeless tyres, this inner layer of less permeable rubber acts as a built-in tube; it prevents air from seeping through casing plies. For tube type tyres, a thinner rubber liner is used to prevent tube chafing against the inside ply.
Tread Reinforcing Ply
This is a rubber compound cushion between tread and casing plies, provides toughness and durability. It adds protection against cutting and bruising throughout the life of the tread.
Sidewalls are primarily the covers over the sides of the cord body to protect the cords from injury and exposure. Little strength is imparted to the cord body by the sidewalls. A special sidewall construction, the "chine tyre," is a nose wheel tyre designed with built-in deflector to divert runway water to the side, thus reducing water spray in the area of rear mounted jet engines.
The apex strip is additional rubber formed around the bead to give a conture for anchoring the ply turn ups.
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