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Anatomy of a Tire

1. Typical Materials Composition of a Tire
2. Typical tire compositions  by Weight
3. Rubber weight by tire component
4. Examples of Rubber Compounds for Tire
5. Steel Tire Cord Analysis


1. Typical Materials Composition of a Tire

     
    This table lists the typical types of materials used to manufacture tires.
    Typical Composition of a Tire

    Synthetic Rubber
    Natural Rubber 
    Sulfur and sulfur compounds 
    Silica
    Phenolic resin 
    Oil: aromatic, naphthenic, paraffinic 
    Fabric: Polyester, Nylon, Etc. 
    Petroleum waxes 
    Pigments: zinc oxide, titanium dioxide, etc. 
    Carbon black 
    Fatty acids 
    Inert materials 
    Steel Wire 


2. Typical tire compositions  by Weight1)

This lists the major classes of materials used to manufacture tires by the percentage of the total weight of the finished tire that each material class represents.

Passenger Tire

 
Natural rubber 14 %
Synthetic rubber 27%
Carbon black 28%
Steel 14 - 15%
Fabric, fillers, accelerators,antiozonants, etc. 16 - 17%
Average weight: New 25 lbs, Scrap 20 lbs.
Truck Tire
 
Natural rubber 27 %
Synthetic rubber 14%
Carbon black 28%
Steel 14 - 15%
Fabric, fillers, accelerators,antiozonants, etc. 16 - 17%
Average weight: New 120 lbs., Scrap 100 lbs.


3. Rubber weight by tire component1)

A tire is manufactured from several separate components, such as tread, innerliner, beads, belts, etc. This table shows which components account for the rubber used to make the tire.

 
RUBBER PERCENT BY WEIGHT IN A NEW RADIAL PASSENGER TIRE
 
TREAD 32.6%
BASE 1.7%
SIDEWALL 21.9%
BEAD APEX 5.0%
BEAD INSULATION 1.2%
FABRIC INSULATION 11.8%
INSULATION OF STEEL CORD 9.5%
INNERLINER 12.4%
UNDERCUSHION       3.9%
  100.0%
4. Examples of Rubber Compounds for Tire2),3)

These examples are chosen to show a diversity of the tire compounds which make it difficult to reuse these into new tire materials.  Each manufactures have developed their own compounds for paticular usage.

 
Tread (PHR) Base (PHR) Sidewall (PHR) Innerliner (PHR)
Natural Rubber
50.0 
100.0
75.0
Styrene-Butadiene Rubber
50.0
25.0
Isobutylene-Isoprene Rubber
100.0
Carbon Black (Grade N110)
50.0
15.0
20.0
Carbon Black (Grade N330)
25.0
35.0
Carbon Black (Grade N765)
50.0
Processing Oil
7.5
5.0
5.0
3.0
Antioxidant 
1.0
0.75
1.0
1.0
Antioxidant Wax
2.0
Stearic Acid
2.0
4.0
3.0
1.5
Zinc Oxidant
5.0
5.0
5.0
5.0
Accelerator (High)
1.0
0.7
Accelerator (Middle)
1.25
0.4
Accelerator (Low)
0.4
Sulfur
2.5
3.0
2.8
2.0
 *PHR = Per Hundred Rubber
 *Carbon grade = ASTM grading : Particle size and structure of carbon are different.


5. Steel Tire Cord Analysis1)

ASTM 1070 Steel Tire Wire

There are approximately 2.5 pounds of steel belts and bead wire in a passenger car tire. This material is made from high carbon steel with a nominal tensile strength of 2,750 MN/m2 and the following typical composition:

 
STEEL BELTS BEAD WIRE
Carbon 0.67 - 0.73% 0.60% min.
Manganese 0.40 - 0.70% 0.40 - 0.70%
Silicon 0.15 - 0.03% 0.15 - 0.30%
Phosphorus 0.03% max. 0.04% max.
Sulfur 0.03% max. 0.04% max.
Copper Trace Trace
Chromium Trace Trace
Nickel Trace Trace
COATING 66% Copper
34% Zinc		 98% Brass
2% Tin


References

  1. Scrap Tire Management Council
  2. James E. Mark, Burak Erman, Frederick R. Eirich. "Science and Technology of Rubber" 1994 Academic Press Inc.
  3. G. Alliger, I. J. Sjothun. "Vulcanization of Elastomers" 1963 Reinhold Publishing Co.


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