How a Tire is Made

How a Tire is Made

The tire manufacturing process might seem complicated – but we’ve made it easy to understand in this section.

Contents:

Introduction

Rubber Compound Mixing Operation

Fabric/Steel Cord Preparation

Belt and Ply Calendering

Innerliner Calendering

Bead Component Preparation

Tire Tread and Sidewall Extrusion Operations

Tire Tread Extrusion

Tire Sidewall Extrusion

Tire Building

Tire Curing

Tire Inspection

Introduction

Tire Cutaway Diagram

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Everyone knows what a tire is and what it’s for, right? It’s a black donut made of rubber, placed on a vehicle so the driver can transport himself and his cargo from point A to point B. The tire has to allow for easy steering, braking and cornering. It must provide for a comfortable, safe ride. It needs to be durable. And that’s about the extent of what most of us know.

Actually, a tire is an advanced engineering product made of a lot more than rubber. Fiber, textile, and steel cord are just some of the components that go into the tire’s innerliner, body plies, bead assembly, belts, sidewalls, and tread. As you can imagine, the manufacture of this complex product is, well, complex. It requires the latest technology, heavy equipment, precision instruments and—most

importantly—qualified people.

Manufacturing Flowchart

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Some of the activities that go on in the tire factory are the mixing of the rubber compound; preparation of the fabric cord, steel cord, and bead wire; “calendering” of the innerliner, steel belt and ply cord; extrusion, or shaping, of the tire’s sidewall and tread; and the actual building, curing, and inspection of the tires. Read on for a more detailed explanation and refer to the manufacturing flowchart for a visual reference to each process.

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Rubber Compound Mixing Operation

Refer to section 1 on the Manufacturing Flowchart.

Rubber compound formulation

The two major ingredients in a rubber compound are the rubber itself and the filler, combined in such a way as to achieve different objectives. Depending on the intended use of the tire, the objective may be to optimize performance, to maximize traction in both wet and dry conditions, or to achieve superior rolling resistance. The desired objective can be achieved through the careful selection of one or more types of rubber, along with the type and amount of filler to blend with the rubber.

In general, there are four major rubbers used: natural rubber, styrene-butadiene rubber (SBR), polybutadiene rubber (BR), and butyl rubber (along with halogenated butyl rubber). The first three are primarily used as tread and sidewall compounds, while butyl rubber and halogenated butyl rubber are primarily used for the innerliner, or the inside portion that holds the compressed air inside the tire.

The most popular fillers are carbon black and silica, and there are several types of each. The selection depends on the performance requirements, as they are different for the tread, sidewall, and apex. Other ingredients also come into play to aid in the processing of the tire or to function as anti-oxidants, anti-ozonants, and anti-aging agents. In addition, the “cure package”—a combination of curatives and accelerators—is used to form the tire and give it its elasticity.

Rubber compound mixing

Once the compound is determined, the next challenge is how to mix it all together. The mixing operation is typically a batch operation, with each batch producing more than 200 kilograms of rubber compound in less than three to five minutes. The mixer is a sophisticated piece of heavy equipment with a mixing chamber that has rotors inside. Its main function is to break down the rubber bale, fillers, and chemicals and mix them with other ingredients.

The sequence in which the ingredients are added is critical, as is the mixing temperature, which can rise as high as 160 - 170 degrees Celsius. If the temperature is too high, the compound can be damaged, so the mixing operation is typically accomplished in two stages. The curative package is normally added in the final stage of mixing, and the final mixing temperature cannot exceed 100-110 degrees Celsius or scorching may occur.

Once the mixing is completed, the batch is dumped out of the mixer and sent through a series of machines to form it into a continuous sheet called a “slap.” The slap is then transferred to other areas for bead wire assembly preparation, innerliner calendering, steel and/or fabric belt/ply cord calendering, tire sidewall extrusion, and tire tread extrusion.

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Fabric/Steel Cord Preparation


Because tires have to carry heavy loads, steel and fabric cords are used in the construction to reinforce the rubber compound and provide strength. Among those materials suitable for the tire application: cotton, rayon, polyester, steel, fiberglass, and aramid.

Fabric cord

Fabric cord quality is based on its strength, stretch, shrinkage, and elasticity. The yarn used is first twisted, and then two or more spools of yarn are twisted into a cord. Before shipping the cord to the tire factory, the manufacturer pre-treats the cord and applies an adhesive to promote good bonding with the rubber. The temperature, humidity, and tension control are critical before the fabric cords are calendered with rubber compound. For this reason, fabric cord is kept in a temperature-and-humidity-controlled room once it arrives at the factory.

Steel cord

Steel wire cord quality is based on tensile strength, elongation, and stiffness. It is manufactured from steel rod with high carbon content; and while the steel wires used have different configurations, all are brass-coated strands twisted together into cords. If the wire is used in a multi-ply tire rather than a belted tire, the fatigue performance will be important. If used in belted tires, then stiffness is of primary concern. Since the steel wire is brass coated, storage conditions are important to maintain the steel wire to rubber bonding properties. Therefore, the steel wires are also kept in a temperature and humidity controlled room once they arrive at the factory.

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Belt and Ply Calendering


To produce fabric or steel belts, the fabric or steel cord must go through a calendering process—an operation in which the rubber compound is pressed on and into cords. Because the bonding of fabric to rubber or steel to rubber is critical to performance, the calendering process is an important step.

The calender is a heavy-duty machine equipped with three or more chrome-plated steel rolls which revolve in opposite directions. The roller temperature is controlled via steam and water. In this process, the rubber compound is applied to the cords.

First, a pre-set number of fabric or steel cords under proper tension are continuously pressed through two steel rollers, and rubber compound is added to the opening area between the rollers. Then the rubber compound is pressed into, on top of and on the bottom of the fabric or steel cords. A continuous sheet of cord-rubber composite goes through several more rollers to ensure good penetration and bonding between the rubber and cords. Quality is measured by the thickness of the sheet, spacing between cords, the number of cords and the penetration of rubber into the composite sheet. The composite sheet is then cut into appropriate sizes, shapes, and angles depending on the desired contour of the tire.

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Innerliner Calendering

The innerliner is just what it sounds like -- the inner-most layer of the tire. Its main functions are to retain the compressed air inside the tire and maintain tire pressure. Due to its low air permeability, butyl rubber—or halogenated butyl rubber compound—is the primary rubber compound used. Because this is a thin layer, it is also produced using the calender. The gauge control and no-defect surface finish are critical to retaining air pressure. Innerliner calendering is also a continuous operation. The proper length of innerliner sheet is pre-cut to be ready for the tire building process.

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Bead Component Preparation


The bead component of the tire is a non-extensible composite loop that anchors the body plies and locks the tire onto the wheel assembly so that it will not slip or rock the rim. The tire bead component includes the steel wire loop, apex or bead filler; the chafer, which protects the wire bead components;

the chipper, which protects the lower sidewall; and the flipper, which helps hold the bead in place. The bead wire loop is made from a continuous steel wire covered by rubber and wound around with several continuous loops. The bead filler is made from a very hard rubber compound, which is extruded so as to form a wedge. The bead wire loop and bead filler are assembled on a sophisticated machine.

The precision of the bead circumference is critical. If too small, tire mounting can be a problem; but if too loose, the tire can come off the rim too easily under loading and cornering conditions. After the circumference is checked, the bead component is ready for the tire building operation.

Tire Tread and Sidewall Extrusion Operations

Tire components such as tread, sidewall, and apex are prepared by forcing uncured rubber compound through an extruder to shape the tire tread or sidewall profiles. Extrusion is one of the most important operations in the tire manufacturing process because it processes most of the rubber compounds produced from the mixing operation and then prepares various components for the ultimate tire building operation.

The extruder in a tire manufacturing process is a screw-type system, consisting primarily of an extruder barrel and extruder head. First, the rubber compound is fed into the extruder barrel where it goes through a heating, blending, and pressurizing process. Then, the rubber compound flows to the extruder head where it is shaped under pressure. The modern cold-feed extruder is computer-controlled for accuracy.

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Tire Tread Extrusion


Tire tread, or the portion of the tire that comes in contact with the road, consists of tread itself, tread shoulder, and tread base. Since there are at least three different rubber compounds used in forming this complex tread profile, the extruder system consists of three different extruders sharing an extruder head. Three rubber compounds are extruded simultaneously from different extruders and are then merged into a shared extruder head. The next move is to a die plate where the shape and dimensions are formed, and then through a long cooling line—from 100 to 200 feet long—to further control and

stabilize the dimensions. At the end of the line, the tread is cut according to a specific length and weight for the tire being built.

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Tire Sidewall Extrusion

The tire sidewall is extruded in a way similar to the tire tread component; however, its structure and the compound used are quite different from tread. Sometimes the sidewall extrusion process can be more complicated, and four extruders may be needed; for example, when building a tire with white sidewalls or with white lettering on the sidewalls.

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Tire Building


Finally, the tire is ready to be built by a highly robotized machine which ensures quality and efficiency. All components—bead assemblies, calendered plies, belts and innerliner, tread and sidewall sections—are assembled and the building process begins.

A typical radial tire is built on a flat drum in a two-stage process. In the first stage, the innerliner is wrapped around a drum and the first body ply is wrapped on top, followed by the second body ply. The bead assemblies are then positioned, and a bladder on the drum is inflated and pushed in from both ends of the drum, forcing the body plies to turn up to cover the bead assemblies. The sidewall sections then are pressed onto both sides.

In the second stage of the tire building process, another machine is used to apply the belts, nylon cap, and tread on top of the first stage. At this point, the tire still needs curing because there is no tread pattern on it.

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Tire Curing


In this final step, curing occurs through a series of chemical reactions. In addition, the sidewalls and tread are molded. Tire curing is a high-temperature and high-pressure batch operation in which the uncured tire is placed into a mold at a specified temperature. After the mold is closed, the rubber compound flows in to mold the shape and form the tread details and sidewall. The mold cannot be opened until the curing reaction is completed.

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Tire Inspection


Tire inspection is the last step in the tire manufacturing process—an important step in ensuring quality in both performance and safety. The tire inspection includes:

Trimming of the mold flash and micro-vents

Visual inspection for appearance and to spot obvious defects

X-ray examination to check internal structure and to spot defects

Tire durability, uniformity, and weight balance inspection

After a tire passes these rigorous inspections, it’s time for the rubber to meet the road! Our tire is ready to be put into service.

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Maintaining your tires takes a little extra time, but nothing is more important for safety and long wear life. Learn about tire care in this section.

Contents:

Tire Technical Information

Tire Safety and Care

Tire Glossary

U.S. DOT Tire Identification Number

Tire Technical Information

Federal law requires tire manufacturers to place standardized information on the sidewall of all tires. This information identifies and describes the fundamental characteristics of the tire and also provides a tire identification number for safety standard certification and in case of a recall.

Tire Sizing

P: Vehicle Type

The "P" indicates the tire is for passenger vehicles.

LT: Vehicle Type The "LT" indicates the tire is for light truck vehicles.

215: Tire Width This three-digit number gives the width in millimeters of the tire from sidewall edge to sidewall edge. In general, the larger the number, the wider the tire.

65: Aspect Ratio This two-digit number, known as the aspect ratio, gives the tire's ratio of height to width in percentage. Numbers of 70 or lower indicate a smaller sidewall for improved steering response and better overall handling on dry pavement.

R: Radial Ply Construction The "R" stands for radial. Radial ply construction of tires has been the industry standard for the past 20 years.

15: Rim Diameter This two-digit number is the wheel or rim diameter in inches. If you change your wheel size, you will have to purchase new tires to match the new wheel diameter.

95H: Load Index This two or three-digit number is the tire's load index. It is a measurement of how much weight each tire can support.

Index Load (lbs) Index Load (lbs) Index Load (lbs)

65 639 94 1477 123 3417

66 661 95 1521 124 3527

67 677 96 1565 125 3638

68 694 97 1609 126 3748

69 716 98 1653 127 3858

70 739 99 1709 128 3968

71 761 100 1764 129 4079

72 783 101 1819 130 4189

73 805 102 1874 131 4299

74 827 103 1929 132 4409

75 853 104 1984 133 4541

76 882 105 2039 134 4674

77 908 106 2094 135 4806

78 937 107 2149 136 4938

79 963 108 2205 137 5071

80 992 109 2271 138 5203

81 1019 110 2337 139 5357

82 1047 111 2403 140 5512

83 1074 112 2469 141 5677

84 1102 113 2535 142 5842

85 1135 114 2601 143 6008

86 1168 115 2679 144 6173

87 1201 116 2756 145 6393

88 1235 117 2833 146 6614

89 1279 118 2910 147 6779

90 1323 119 2998 148 6944

91 1356 120 3086 149 7165

92 1389 121 3197 150 7385

93 1433 122 3307

Note: You may not find this information on all tires because it is not required by law.

Light truck sizes may be shown in two formats:

LT 245/70R16

LT = Vehicle type

245 = Width in millimeters

70 = Aspect ratio

R = Radial construction

16 = Rim diameter in inches

32x11.50R16 LT

32 = Diameter in inches

11.50 = Width in inches

R = Radial construction

16 = Rim diameter in inches

LT = Light truck tire

Tire Speed Rating Chart

The rating system shown indicates the top speed for which a tire is certified. It does not indicate the total performance capability of a tire.

The speed rating denotes the speed at which a tire is designed to be driven for extended periods of time. The ratings range from 31 miles per hour (mph) to 188 mph.

Note: You may not always find this information on all tires because it is not required by law.

Rating Symbol Speed (km/h) Speed (mph)

B 50 31

C 60 37

D 65 40

E 70 43

F 80 50

G 90 56

J 100 62

K 110 68

L 120 75

M 130 81

N 140 87

P 150 93

Q 160 99

R 170 106

S 180 112

T 190 118

U 200 124

H 210 130

V 240 150

W 270 169

Y 300 188

ZR Over 240 Over 150

M+S = Mud and Snow

The "M+S" or "M/S" indicates that the tire has some mud and snow capability. Most radial tires have these markings; hence, they have some mud and snow capability.

U.S. DOT Tire Identification Number

This begins with the letters "DOT" and indicates that the tire meets all federal standards. The next two numbers or letters are the plant code where it was manufactured, and the last four numbers represent the week and year the tire was built. For example, the numbers 1301 mean the 13th week of 2001. The other numbers are marketing codes used at the manufacturer's discretion. This information is used to contact consumers if a tire defect requires a recall.

For example: DOT "UYZEDBC1301"

UY: Plant code

ZE: Tire size

DBC: Compound structure code (Optional)

13: The week manufactured

01: The year manufactured

Tire Ply Construction and Materials Used

The number of plies and cords indicates the number of layers of rubber-coated fabric or steel cords in the tire. In general, the greater the number of plies, the more weight a tire can support. Tire manufacturers also must indicate the cords used in the tire, which include steel, nylon, polyester, and others.

Maximum Load Rating

This number indicates the maximum load in kilograms or pounds that can be carried by the tire.

Maximum Permissible Inflation Pressure

This number is the maximum amount of air pressure that should ever be put in the tire under normal driving conditions.

What is UTQG?

UTQG stands for the Uniform Tire Quality Grading system.

To help consumers compare a passenger car tire's treadwear rate, traction performance, and temperature resistance, the federal government requires tire manufacturers to grade tires in these three areas. This grading system, known as the Uniform Tire Quality Grading System, provides guidelines for making relative comparisons when purchasing new tires. You also can use this information to inquire about the quality of tires placed on new vehicles.

Although this rating system is very helpful when buying new tires, it is not a safety rating or a guarantee of how well a tire will perform or how long it will last. Other factors such as personal driving style, type of car, quality of the roads, and tire maintenance habits have a significant influence on your tire's performance and longevity.

Treadwear grades are an indication of a tire's relative wear rate. The higher the treadwear number, the longer it should take for the tread to wear down. For example, a tire grade of 400 lasts significantly longer than a tire grade of 200

Traction grades are an indication of a tire's ability to stop on wet pavement. A higher graded tire should allow you to stop your car on wet roads in a shorter distance than a tire with a lower grade. Traction is graded from highest to lowest as "AA," "A," "B," and "C."

Temperature grades are an indication of a tire's resistance to heat. Sustained high temperature (for example, driving long distances in hot weather), can cause tire failure. From highest to lowest, a tire's resistance to heat is graded as "A," "B," or "C."

Example:

A Maxxis MA-1 should have a UTQG rating of 480 BB and deliver a high level of mileage expectation along with a smooth, quiet ride. On the other hand, a Maxxis MA-501 has a UTQG rating of 300 AA and is more in line with the expectations of a performance tire.

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Tire Safety and Care

To ensure your safety, Maxxis recommends replacing your tires with the original size or the size recommended by your automobile’s manufacturer. The "Tire Finder" locator section of this website only recommends the original equipment sizes.

View the Tire Inspection Chart for information on how to identify abnormal tread wear, sidewall damage, tire separations, road hazards and bead problems.

When purchasing new tires, it is recommended the tires be mounted by a professional; do not attempt to mount them yourself. Serious injury could result from a tire being mounted improperly. While mounting new tires, the dealer can inspect the vehicle, rim, brakes, etc., for any potential problems as well as recommend the proper inflation, correct positioning, and correct tire size.

Maxxis recommends that P-Metric automotive tires never be used as replacements for Light Truck tires or on a vehicle that is equipped with dual rear tires. Each tire is manufactured with specific speed rating and load requirements to ensure proper vehicle use.

Measuring the Width of a Tire

In some cases, the tire width might need to be measured. Before the measurement is taken, Maxxis recommends the tire be mounted on the rim recommended by the Tire and Rim Association (T&RA) for accurate measurement.

If the tire is mounted on a rim that is too narrow, the tire will have a measurement that is too narrow. This could possibly put an increase of force on the shoulder of the tire, resulting in tire damage. If the tire is mounted on a rim that is wider than recommended by the Tire and Rim Association, the tire will have a flatter profile, moving the flex point toward the area of the rim. The resulting heat buildup can cause a decrease in tire life or integrity.

As with any changes or variations done in regards to tires and rims, always consult with your certified Maxxis dealer first.

Aspect Ratios

Higher aspect ratios provide a softer ride and an increase in deflection under the load of the vehicle. However, a lower aspect ratio, normally used for higher performance vehicles, has a wider contact patch and a faster response. This results in less deflection under a load, causing a rougher ride to the vehicle.

Changing to a tire with a different aspect ratio will result in a different contact patch, therefore changing the load capacity of the tire. This change in load capacity should always be taken into consideration when changing tire sizes.

Tire Rotation

Always refer to your owner’s manual for a rotation schedule and pattern specific to your vehicle. However, a good rule of thumb is to rotate your tires about every 6,000-8,000 miles in order to avoid irregular tire wear.

Balancing Your Tires

When tires are unbalanced, ride quality and tire life are significantly impacted. An unbalanced tire is usually detectable by vibrations at certain speeds. Typically, the vibration is felt through the steering wheel, especially at high speeds.

Hitting curbs, potholes, or other road hazards may create an unbalance in the tire. Tires should be inspected by a professional as soon as possible to avoid excessive wear and damage to your vehicle’s front end parts.

Alignments

Aligning your tires ensures that all of them are adjusted to travel in the same direction. Improper alignment affects tire wear, gas mileage, stability, and the overall performance of your vehicle. You should have an alignment performed on your vehicle about once a year, although hitting a curb or pothole may throw your alignment out. If this happens, you should have a tire professional inspect your alignment as soon as possible.

Reasons to suspect your tires need to be aligned and to have your alignment checked:

Excessive or uneven tire wear

Steering wheel pulls to the left or right

Feeling of looseness or wandering

Steering wheel vibration or shimmy

Steering wheel is not centered when car is moving straight ahead

Proper Tire Inflation

Proper tire inflation ensures your tires will perform better, last longer, and increase your gas mileage. Always use a tire gauge to check the pressure in your tires while they are still cold. It is good practice to check your pressure at least once a month or before long trips.

Your vehicle manufacturer will specify the inflation pressure necessary for your OE tires. Check with your tire dealer if you no longer have OE tires installed.

Cleaning Maxxis Tires

To ensure Maxxis tires look their best, the sidewalls are constructed to defend against the elements. To keep them looking their best, use a mild soap or detergent and a semi-soft bristle brush. To rinse, use clean, plain water.

Overloading Tires

IMPORTANT - Make sure you don’t overload tires. To make certain you’re within safety limits, check the vehicle owner’s manual to determine the amount of load put on the tires. From there, check the load limit of the tires that are to be mounted. The load index of the replacement tires should always meet or exceed the maximum load of the original tires. The overloading of tires could cause poor vehicle handling, tire failure, and/or problems with vehicle components or lower fuel mileage.

Tire Mounting

IMPORTANT – Because of the nature of tire mounting, Maxxis recommends tires always be mounted by a professional. Make sure to match tire diameter to rim diameter and mount light truck radials on rims only approved for that application.

It is our recommendation that bead sealer not be applied as this can inhibit the seating of the bead. Lubricate beads and tire rim contact surfaces. Lock assembly on mounting machine or place in safety cage. Step back, and never exceed the amount of necessary air pressure to seat the bead. Do not use a volatile substance, a bead expander, or "O-Ring" to help in seating a bead.

Mounting a tire to rims can be very dangerous due to the energy stored in compressed air. Only trained tire professionals using the correct tools, safety equipment, and procedures should mount tires. Do not re-inflate a tire that has been run flat or shows any signs of damage. Incorrectly mounted or damaged tires can suddenly cause tire failure, resulting in injury.

Consistent Tire Sizing

Maxxis strongly urges that all tires mounted on a vehicle coincide with the recommendations of the vehicle manufacturer. Also, Maxxis recommends that all tires mounted be of the same type and size.

However, if different profiles must be used, mount the widest tires in the rear of the vehicle. For the best handling characteristics, do not mix radial tires with non-radial tires. Mounting tires of different speed ratings, sizes, or construction could result in tire failure.

Tire Wear

Maxxis recommends tires be removed from the vehicle when there is only 2/32" of tread depth remaining. All DOT approved tires in production have a tread wear indicator molded into the tread pattern. This small piece of rubber appears to be a bridge between two tire grooves, but is only 2/32” in height. When the top of this indicator is even with the plain of the tread pattern, the tires should be

replaced. Failure to replace tires with tread depths less than 2/32” could result in accidents due to loss of traction.

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Tire Glossary

Accelerator: A chemical that is used in rubber compounds.

Adjustment: An allowance given to a customer to be used toward the replacement of a tire because of warranty issues.

Alignment: Inspection and the possibility of adjusting the caster camber and toe angles of the automobile’s suspension system in accordance with the manufacturer’s original specifications.

Antioxidant: A chemical used in rubber compounds that prevents surface oxidation, chunking, and cracking.

Aspect Ratio: The measurement of a tire’s sidewall height. The calculation is derived from dividing the section height by the section width of the tire.

Balance: To ensure weight is distributed evenly around the tire and rim, resulting in a smoother ride.

Banbury Mixer: A large machine used in the production of rubber compounds for mixing all of the filler and ingredients together.

Bead: The part of the tire that secures the tire to the rim, normally constructed from a high grade steel wire and hard rubber compound.

Bead Seat: The section of a rim where the bead of the tire rests.

Belts: These are layers of fabric or steel cords coated in a rubber compound providing the tire with its strength.

Bias-Ply: A type of construction method used to build tires where the cords in the body plies are placed diagonally from one side of the tire to the other, normally from one bead to the opposite bead.

Bladder: A large, rubber, inflatable container used in the tire molding and curing process of tire production.

Blem of Blemished Tire: A tire which has cosmetic or minor imperfection but is still considered safe to use.

Bolt Pattern: The pattern of holes on a rim/wheel which the bolts that mount the wheel to the vehicle are put through.

Camber: The angle of the vertical center of the tire to a vertical line viewed from the front of the tire.

Camber Thrust: The force created by a tire’s camber.

Carbon Black: Filler used in the rubber compounds. Its primary function is to be used as reinforcement filler.

Carcass: This is the body that gives the tire its shape.

Carrying Capacity: The amount of load/weight a tire can carry at its proper inflationary pressure established by the Tire & Rim Association.

Chafer: A rubber-coated, abrasion-resistant material that is used to aid in preventing a tire’s bead from rim damage and chafing.

Compound: The mixture of ingredients such as natural rubber, synthetic rubber, carbon black, and chemicals, put together in different ratios to form the building block from which tires are manufactured.

Contact Patch: The area of the tire that makes direct contact with the surface of the road.

Cord: The steel or fabric strands that form plies and belts in tires.

Cord Angle: The degree of angle that the cords cross the center line of a tire.

Crown: The center section (between the tire shoulders) of the tire’s tread.

Deflection: The change in the tire’s vertical and lateral dimensions when it is placed under load.

Directional Stability: The tendency for a tire to move in the direction it is steered to rather than following the contours of the road.

Diameter: The measurement of an unloaded tire from one outer edge to the opposite edge.

Dynamic Balance: This is the balance of a tire while in motion.

Eccentric Mounting: A condition where a tire is mounted unevenly on a rim/wheel.

ETRTO: European Tire and Rim Technical Organization.

Flotation Tire: A tire designed to do minimal damage to the lawn or soil surface.

Green Tire: A tire that has not yet gone through the process of vulcanization or curing in the tire molding process.

Grooves: Channels in the tread pattern that allow water to flow out from underneath the tire for wet weather driving.

Hoop Strength: The strength in the construction of the belt of a tire is resistant to centrifugal strength, giving the tire stability.

Hydroplaning: A loss of traction of a tire on a road surface caused by wet weather conditions.

Inflation Pressure: The pressure of air inside the tire.

Innerliner: A layer of rubber inside the tire carcass that retains the air in a tire.

Load Index: A numbering system that specifies the maximum amount of weight a tire can carry at the speed indicated by the speed rating.

Load Range: This term replaces the former ply rating system and provides the load and inflation limits of a tire.

LT-Metric: A sizing system used for light truck.

Match Mounting: A system of mounting a tire where the high point of the tire is matched with the low point of a wheel. These spots are normally designated by a dot or a sticker on the tire and wheel.

Mounting Tires: The action of putting the tire on a rim. This should only be done by a professional for safety reasons.

M+S, M/S, M&S: A designation of a tire that meets the requirements given by the RMA to be used in mud and snow conditions.

NHTSA: National Highway Traffic Safety Administration.

O.E.: This refers to the original equipment of the vehicle.

Over Inflation: A tire that exceeds the maximum amount of air pressure recommended by the manufacturer.

Out of Round: A term used to indicate that the tire is not completely round.

P-Metric: A tire sizing system where the section width is shown in millimeters and the aspect ratio, type of construction, and rim diameter are shown in inches (P215/70R15)

Plies: The layers of rubber-coated fabric or steel cord.

Polyester: This is a synthetic material that is used in the body ply or belt of a tire.

Polymer: A high molecular weight organic compound made up of many identical components which link to form a chain through a process called polymerization.

PSI: A measure of air pressure – pounds per square inch.

Radial: A construction method used to build tires where cords of steel are coated in rubber and are laid across the crown of the tire at an angle of 90 degrees.

Rayon: A synthetic cord material used in the construction of casings and belts of a tire.

Retread: A process in which a new tread cap is applied to a casing of a tire that has been worn down.

Rim: The piece of hardware a tire is mounted on and then placed on the automobile or truck.

Rim Diameter: The diameter of the rim measured according to the tire bead heel.

Rim Flange: The outermost edge of a wheel’s rim where additional weights for balancing the tire are positioned.

Rim Width: The distance between the flanges of a wheel.

RMA: Rubber Manufacturers Association.

Runout: The measurement of the "out of roundness" of a tire that causes vibration and cannot be balanced.

Section Height: The vertical distance measured from the edge of the bead to the center of the crown in a tire that is not under load.

Section Width: The measurement of a mounted tire from the outside of one sidewall to the outside of the opposite sidewall.

Series: The designation of a tire’s aspect ratio.

Shoulder: The section of a tire where the tire tread is adjoined to the sidewall.

Sidewall: The section of a tire between the bead and the shoulder.

Sipes: Small, thin slots that are molded into the ribs or blocks of a tread pattern that aid in the traction of the vehicle in wet weather conditions.

Speed Rating: A letter coding system designated by the Tire & Rim Association indicating the tire’s durability at a particular speed.

Static Balance: A condition in which a mounted tire has even weight around the wheel's axis when the tire is not in motion.

Steel Belt: A layer of material constructed from steel cords and normally coated in rubber, placed on top of the casing used in the production of tires.

Toe: This is the difference between the front and the rear edges of a tire mounted on an automobile. If the front edges are closer together than the rear edges, the phrase toe-in is used. If the front edges are farther apart than the rear edges, it is referred to as toe-out.

Tread: The section of the tire that is in contact with the road surface.

Tread Life: The length of service, measured in miles, of a tire.

Tread Pattern: This is the configuration of voids, blocks, grooves, sipes, etc. of the tread constructed to provide some of the characteristics of a tire.

Tread Void: Areas in a tread such as grooves and channels permitting water to be moved away.

Tubeless Tire: A tire that does not require an inner tube. This type of tire construction utilizes an innerliner inside the casing, preventing air leakage.

Tread Wear Indicators(T.W.I.): Small tread blocks in a tire’s tread pattern (the void area) measuring 2/32" in height that show when a tire should be changed.

Tread Width: The measured distance from the outer edge of a tire’s tread pattern to the opposite edge of the tread pattern.

Under Inflation: A tire that has a lower amount of air pressure than recommended by the manufacturer.

UTQG: Uniform Tire Quality Grading – A measuring system to compare a tire’s performance based on test results for treadwear, temperature resistance, and traction.

Zero Toe: A condition where tires on the same axle are positioned exactly parallel to each other.

Documents

How a Tire is Made