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Construction Components
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Construction materials used by each
tire manufacturer are chosen with their own technology in mind.
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Each component of a tire is designed
to provide benefits specifically related to its function, while
working together with all other components. Example:
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The belt system's
main function is to provide stability to the tread area of the
tire, which contributes to wear, handling and traction.
The belt system must also work in unison with the tire's
sidewall and tread to achieve traction and cornering
capabilities.
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Tire components are assembled like a
puzzle and molded together in the curing process.
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This process causes all of the tire
components and rubber compounds to adhere to their surrounding
components, resulting in a singular product.
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Tire Casing
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The tire casing is the body of the
tire.
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Most passenger tire casings are one or
two body plies.
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The tire casing incorporates fabric of
polyester, nylon or rayon cords within the casing rubber compound.
These cords add strength to the casing rubber.
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Weight is an important factor in
virtually all tire components. The heavier a tire is, the higher the
potential for building up heat during operating conditions. An
excess build up of heat in a tire eventually causes the rubber
compounds to break down.
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Polyester is the most common casing
fabric used and
provides: Good Rubber Adhesion, Excellent strength, Good Ride
Characteristics
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Polyester provides these features at a
relatively low weight, while exhibiting heat dissipation
characteristics.
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Other fabric materials used in the
tire casing include nylon and rayon, which exhibit benefits similar
to polyester.
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Most passenger tires manufactured
today are radials. Prior to radial construction, bias and bias
belted construction was used.
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The Belt System
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The belt system is placed on top of
the casing in the construction process.
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The belt system's main function is to
provide stability to the tread area of the tire, which contributes
to wear, handling and traction.
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The most common belt material used is
steel. Steel belts provide strength and stability to the tread area
without adding a lot of weight to the tire.
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Usually two plies of steel cord placed
at a bias angle make up the belt system.
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The most common belt configuration is
two plies of steel cord stacked, one on top of the other.
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The
Tread
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The tread slab is placed on top of the
belt system in the manufacturing process.
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The tread usually contains two rubber
compounds:
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The tread base compound adheres to
the belt system when the tire is cured, is cooler running
improving durability and helps stabilize the undertread area of
the tire.
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The treadcap is typically made
with an abrasion resistant, higher grip rubber compound, which
works with the tread base and tread design to provide
traction and mileage.
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The tire's tread design is molded into
the treadcap rubber during the curing process.
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The
Sidewall
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A special rubber compound is used in
the sidewall of the tire, which adds flexibility and weathering
resistance.
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Some tires, such as higher end
performance tires, may also incorporate steel and/or nylon inserts
to provide quicker steering response.
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The
Innerliner
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The
Bead
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Tire bead bundles secure the tire to
the wheel. They are large monofilament steel cords that are wound
together to form a cable or ribbon-type configuration.
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The casing plies are looped around the
bead bundles holding them in place.
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Bead filler, a rubber compound, is
incorporated within the bead configuration and extends up into the
sidewall area.
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The rubber compound used on the
outside bead area is usually a hard, durable compound that
withstands the rigors of mounting and chafing.
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Passenger
Tire vs. Light Truck Tire Construction
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Differences between passenger and
light truck construction are due to the different uses and operating
conditions of light trucks versus automobiles.
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Light trucks are usually designed to
operate in more severe conditions, such as carrying greater loads
more of the time and going off-road.
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Light truck tires may have an extra
casing ply, an extra belt, a stronger belt steelcord and/or a larger
bead with more sidewall rubber. This is why light truck tires tend
to be heavier than passenger tires.
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Some light truck tires are also
capable of higher air pressures and load carrying capacities.
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