Tire Construction

Construction Components 

• Construction materials used by each tire manufacturer are chosen with their own technology in mind.
• Each component of a tire is designed to provide benefits specifically related to its function, while working together with all other components. Example:

  • 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.

• Tire components are assembled like a puzzle and molded together in the curing process.
• 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 

• The tire casing is the body of the tire.
• Most passenger tire casings are one or two body plies.
• The tire casing incorporates fabric of polyester, nylon or rayon cords within the casing rubber compound. These cords add strength to the casing rubber.
• 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.
• Polyester is the most common casing fabric used and
  provides: Good Rubber Adhesion, Excellent strength, Good Ride Characteristics
• Polyester provides these features at a relatively low weight, while exhibiting heat dissipation characteristics.
• Other fabric materials used in the tire casing include nylon and rayon, which exhibit benefits similar to polyester.
• 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 

• The belt system is placed on top of the casing in the construction process.
• 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 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.
• Usually two plies of steel cord placed at a bias angle make up the belt system.
• The most common belt configuration is two plies of steel cord stacked, one on top of the other.

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The Tread 

• The tread slab is placed on top of the belt system in the manufacturing process.
• The tread usually contains two rubber compounds:
  • 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.
  • 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.
  The tire's tread design is molded into the treadcap rubber during the curing process.

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The Sidewall 

• A special rubber compound is used in the sidewall of the tire, which adds flexibility and weathering resistance.
• 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 

• A rubber compound is used as an air seal inside the tire. This innerliner layer has no cord reinforcing and serves a similar function as an innertube.

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The Bead 

• 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.
• The casing plies are looped around the bead bundles holding them in place.
• Bead filler, a rubber compound, is incorporated within the bead configuration and extends up into the sidewall area.
• 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 

• Differences between passenger and light truck construction are due to the different uses and operating conditions of light trucks versus automobiles.
• Light trucks are usually designed to operate in more severe conditions, such as carrying greater loads more of the time and going off-road.
• 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.
• Some light truck tires are also capable of higher air pressures and load carrying capacities.

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