轮胎工艺英语

Tire Manufacturing Process

Tires are not just round and black they are sophisticated products that can take years of research and development to produce. If you have ever wondered how tires are made, the following is a roadmap for the construction of a radial tire:

Start with Rubber and Additives

Tire construction starts when raw chemical additives such as sulfur, carbon black and solvents are combined with natural and synthetic rubber. The process takes place in a large machine called a banbury.

In addition to mixing and grinding, the banbury heats the rubber to make it workable in preparation for further applications. The raw product emerges in the form of long, flat bands of rubber, which are then worked in rolling mills.

Six Main Components

It takes several machines to shape the rubber into the individual components of the tire: tread, ply, belts, beads, sidewalls, and innerliner.

?The tread rubber is extruded through a tuber, then measured, cooled and cut into precise lengths.

?Sidewalls are also extruded through tubers, along with the white rubber for a white sidewall or white lettered tire if required.

?The ply is produced in a calender mill, which combines thin sheets of rubber with nylon or polyester cord fabrics. The large sheets are cut to width, rolled and transported to the assembly area where all the components will come together.

?At the same time as the raw rubber is transformed into the tread and plies, the creel room equips the tire with its basic strength.

Fine steel wire goes into the manufacture of belts for the

steel-belted radial tire. Rubber from the mills and steel from the creel room are molded together into wide flat sheets, cut on the bias, rolled, and moved to the tire-building machine.

?The innerliner is a impermeable layer of rubber on the inside of

a tire which creates a airtight chamber when fitted to the vehicle

wheel. This layer eliminates the need for a innertube.

?The last major component of the tire is the bead. The beads are created out of wrapped steel wire, covered with rubber and formed into hoops. The bead anchors the fabric plies of the tire and seats the tire firmly on the wheel.

The Green Tire

The six components (tread, ply, belts, sidewalls, liner and beads) come together on the tire-building machine. These six components are assembled into what is known as an uncured, or green, tire in two stages.

?The carcass of the tire, including beads, plies, sidewalls and liner, is constructed on one side of the machine.

?The tread and the underlying belts are assembled next to the carcass on the other side of the machine.

The two subassemblies are then joined together and the result is a green tire.

Vulcanization

The next phase is vulcanization, the molecular transformation of the soft, gummy green tire into the tough, and longwearing, modern passenger tire. The green tire is placed in a curing mold and is subjected to intense pressure and high heat internally and externally for a specified period of time. Simultaneously, the tread pattern is imprinted onto the rubber. When it comes from the mold, the tire is ready for final finish and inspection.

Final Finish and Inspection

For showroom quality, any excess rubber is trimmed off the cured tire. Every tire is thoroughly inspected. The tire then undergoes various uniformity checks to assess ride and comfort quality. Once the tires have passed all the checks and inspections, they are sent to the distribution warehouse for shipment.

How To Read Tire Sidewall

P205/55R16

91W

Tire Size

Example: P205/55R16 91W

P P identifies your tire as a Passenger Tire. The P stands for PMetric. If your tire size starts with LT rather than a P than

it identifies the tire as a light truck tire.

205 205 identifies the tire section width, which is the

measurement of the tire from sidewall to sidewall in

millimeters. This measurement varies depending on the rim to

which it is fitted.

(There are 25.4 millimeters per 1 inch.)

55 55 is the two-figure aspect ratio. This percentage compares

the tire's section height with the tire's section width. For

example, this aspect ratio of 55 means that the tire's section

height is 55% of the tire's section width.

R R indicates the construction used within the tire's casing.

R stands for radial construction. B means belted bias and D

stands for diagonal bias construction.

16 16 The last dimension listed in the size is the diameter of

the wheel rim which is most often measured in inches. Load Index and Speed Rating

91W 91W The load index and speed rating, or service description are the numbers that follow the tire size.

The load index tells you how much weight the tire can support

when properly inflated. Load indices range from 74 - 150 for

passenger tires with each numeric value corresponding to a

certain carrying capacity. The carrying capacity for each

value can be found on a load index chart. On each U.S. passenger

car tire, the load limit is listed in pounds. European tires

have the load limit listed in kilograms and sometimes pounds.

Speed Ratings Speed ratings are represented by letters ranging from A to Z. Each letter coincides to the maximum speed a tire can sustain under its recommended load capacity. For instance, S is equivalent to a max speed of 112 mph. Even though a tire can perform at this speed, we do not advocate exceeding legal speed limits.

Speed Symbol Speed(km/h) Speed(mph) A1 5 3

A2 10 6

A3 15 9

A4 20 12

A5 25 16

A6 30 19

A7 35 22

A8 40 25

B 50 31

C 60 37

D 65 40

E 70 43

F 80 50

G 90 50

G 90 56

J 100 62

K 110 68

L 120 75

M 130 81

N 140 87

P 150 94

Q 160 100

R 170 106

S 180 112

T 190 118

U 200 124

H 210 130

V 240 149

W 270 168

Y 300 186

(Z) 300 186

DOT Serial Number

The "DOT" symbol certifies the tire manufacturer's compliance with the U.S. Department of Transportation tire safety standards. Below is a description of the serial number. Starting with the year 2000, four numbers are used for the Date of Manufacture, first two numbers identify the week and the last two numbers identify the year of manufacture.

Prior to year 2000 three numbers are used for the Date of manufacture, first two numbers identify the week and the last number identifies the

year of manufacture. To identify tires manufactured in the 90's a decade symbol (a triangle on its side) is located at the end of the DOT serial number.

Tire Maintenance Tips

Your tires are the only part of your vehicle that actually touches the road when you drive. It only takes a couple of minutes of maintenance each month to keep your tires working at their best.

Check Your Air Pressure Once a Month

Incorrect air pressure is the leading cause of tire damage. To avoid tire damage you need to check your tire's air pressure once a month.

The correct tire pressure is listed on the vehicle placard & can be found in the following places:

?The car's owner manual

?Inside the gas tank lid

?On the edge of the driver's side door

?On the door post

The air pressure listed on the side of your tire is NOT the correct air pressure for your vehicle. That number is the maximum air pressure for the tire. Remember to check the air in your spare tire.

Don't get stranded or put out costly towing expenses. Check your air pressure on your spare regularly. Note: If you have different rims than came on your vehicle originally, make sure that the bolts on your spare tire are the correct fitting.

Failure to keep your tires properly inflated can increase wear and will have a negative effect on your vehicles handling.

When checking and adjusting tire pressure, the following should be kept in mind:

?Check the air pressure when the tire is cold - tires become hot even after driving just a mile. If you must drive to add air, check your air pressure before you leave. Air pressure changes 1-2 pounds for every 10 degrees of temperature change. Air pressure goes up in warm weather and down in cold weather.

?Tire pressure must be the same on the tires of each axle, but may be different on the front and rear axle.

?Valve caps must be tightly closed to protect the valve from dust and dirt and prevent it from leaking.

?Replace missing valve caps without delay.

Take this opportunity to inspect your tires to make sure there is nothing stuck in them or they have no deformities.

Tread Depth

To prevent hydroplaning and skidding your tires must have proper tread depth. The minimum tread depth is 1/16th of and inch.

Ask anyone, the easiest way to check your tread depth...the penny test. What is the penny test? Take a penny and place it in the tread of your tire. If part of Lincoln's head is covered by the tread your tires have enough tread. If you can see Lincoln's entire head, you should buy a new tire.

You should also check your tire tread for uneven wear. Irregular wear shortens the life of your tires, if you think you have uneven wear you should take you vehicle to your tire dealer.

Rotation

The best way to prevent uneven wear is to have your tires rotated every 6,000 - 8,000 miles or as specified in your vehicle's owner manual.

Potential Tire Troubles

?Curbs can prove to be big trouble to your tires. Approach curbs with care, if you drive over them too fast or at the wrong angle the impact may cause the tire to crack.

?Avoid potholes or debris in the road when possible.

?Avoid fast stops & starts.

?Be sure to check your owner's manual for your vehicles maximum load.

Overloading your vehicle can shorten your tires life. Replacing Your Tires

You should replace your tires with the same type of tires that came on your vehicle original equipment. This includes tire size, type and speed rating.

History of Tires

The Evolution of the Passenger Tire

Dateline 3500 B.C.--Today man invented the greatest invention ever seen, THE WHEEL!

Thousands of years later, the wheel has come a long way. For one thing it is no longer made of wood and it is guaranteed that the ride is much smoother. What hasn't changed is the fact it is still one of man's greatest inventions. Could you even imagine where we would be today without it?

The early wheel was very simple...a solid curved piece of wood, then leather was eventually added to soften the ride, as time progressed it became solid rubber which led to today's tire--the pneumatic, or air inflated, radial tire.

The first wheels made of metal or wood were very durable but did not provide a very comfortable ride. The nearest thing to the first tire was a metal hoop. There were many individuals that made contributions in creating the tire as we think of it today.

Vulcanization and Charles Goodyear

Rubber was not always as useful as it is today. Early rubber did not hold shape; it would be sticky in hot weather and become inflexible in the cold.

In 1839 Charles Goodyear was credited with the discovery of the vulcanization process. Vulcanization is the process of heating rubber with sulfur. This transforms sticky raw rubber to firm pliable material which makes rubber a perfect material for tires.

The story of Charles Goodyear is a sad one, although he dedicated his entire life to making rubber a better form he would never profit from all his work. Charles Goodyear died bankrupt.

Forty years later a rubber company would honor his hard work by using his name for their new tire company.

Solid Rubber Tires

Soon, after the discovery of vulcanization tires were made out of solid rubber. These tires were strong, absorbed shocks and resisted cuts and abrasions. Although they were a vast improvement, these tires were very heavy and did not provide a smooth ride.

Today there are still types of tires made of solid rubber. Pneumatic Tires

The pneumatic rubber tire uses rubber and enclosed air to reduce vibration and improve traction. Robert W. Thomson, a Scottish engineer, first patented the air filled tire. Unfortunately the idea was too early for its time and was not a commercial success.

In 1888 John Boyd Dunlop of Belfast, Ireland became the second inventor of the pneumatic tire. Dunlop claimed to have no knowledge of Thomsons earlier invention.

The second time around the pneumatic tire caught the publics attention. The timing was perfect because bicycles were becoming extremely popular and the lighter tire provided a much better ride.

Bias Ply Tires

For the next fifty years vehicle tires were made up of an inner tube that contained compressed air and an outer casing. This casing protected the inner tube and provided the tire with traction.

Layers called plys reinforced the casing. The plys were made of rubberized fabric cords that were embedded in the rubber. These tires were known as bias-ply tires. They were named bias ply because the cords in a single ply run diagonally from the beads on one inner rim to the beads on the other. However, the orientation of the cords is reversed from ply to ply so that the cords crisscross each other.

Today you can still find bias-ply tires as authentic equipment for antique and collector cars, as well as for certain type of off-the-road tractor tires.

Radial Tires

Michelin invented radial tires in 1948 and they were first introduced in Europe that year. Radial tires are so named because the ply cords radiate at a 90 degree angle from the wheel rim, and the casing is strengthened by a belt of steel fabric that runs around the circumference of the tire.

Radial tire ply cords are made of nylon, rayon, or polyester. The advantages of radial tires include longer tread life, better steering and less rolling resistance, which increases gas mileage. On the other hand, radials have a harder riding quality, and are about twice as expensive to make.

Tire Terminology

?Air Pressure

?Alignment of Vehicle

?All Season Tires

?ABS/Anti-Lock Brake System

?ASR/Anti-Slip Control

?Aquaplaning

?Balancing

?Bead

?Braking Distance

?Camber

?Casing

?Chains

?Date of Manufacture

?Direction of Rotation

?DOT Serial Number

?ESP/Electronic Stability Program

?Emergency Mobility Systems

?Load Index, Ply Rating or Load Range

?Mixing Tires

?Radial Tires

?Reinforced or XL (extra load) Tires

?Revolutions Per Mile (RPM)

?Rolling Resistance

?Rotation

?Speed Symbol

?Temporary Spare Tires

?Toe

?Tread

?Tread Depth

?TWI (Tread Wear Indicator)

?Tire Size Designation

?Tire Storage

?UTQG (Uniform Tire Quality Grading

?Valve

?Valve Cap

?Winter Tires

Air Pressure

CHECK the pressure in your tires at least monthly and before long trips when your tires are cool (after the vehicle has been stopped 3 hours and then driven less than one mile). Adjust to the vehicle manufacturers specified pressure while tires are cold. Never bleed or reduce air pressure when tires are hot. It is normal for pressure to build up as a result of driving. Use an accurate tire gauge to check pressure and maintain it at the level recommended by the vehicle manufacturer. Dont forget your standard size or temporary spare tire. Your temporary spare - it requires a higher inflation pressure. Remember: Under inflation is the most common cause of sudden air loss or sudden failures in any kind of tire and may result in unexpected loss of vehicle control or accidents.

Alignment of Vehicle

A wheel alignment adjustment may be necessary if the vehicle pulls to the right or the left with the steering wheel is in straight ahead position. Another indicator of the need for an alignment check is if tires are wearing unevenly.

All Season Tires

All season tires can be used throughout the year. The following markings appear on the sidewall of the tire: M+S, M/S or M&S. This meets the RMA definition of a mud and winter tire. However, there are also tires designed for severe snow conditions. These tires will show a symbol of a mountain with a snowflake next to the MS letters & are designed as winter tires.

Tires designed for use in severe snow conditions generally have tread patterns, structure and materials to give superior performance. These tires are marked with the "M+S" designation plus a mountain/snowflake symbol.

ABS / Anti-Lock Brake System

Under emergency braking using conventional braking systems the wheels can lock up, making the car un-steerable. ABS systems provide continuous monitoring and control of the braking force and in some circumstances can reduce the braking distance while maintaining full car steer ability.

Modern high-quality tires are optimized and matched to the ABS functions. And "braking on wet roads with ABS and ABS-brakes" are already often a standard test required by auto manufactures for many tire test specifications.

ASR / Anti-slip-control

ASR is fitted to vehicles to prevent wheels slipping, spinning on slippery or uneven surfaces.

Electronic sensors are used to control and dose the power transmitted to the drive axle, in order to ensure that tires can properly and reliably grip the road during acceleration.

Aquaplaning

The contact area of the tire to the road is reduced when by water is on the road. In extreme cases, the vehicle "hydroplanes (glides) on the water". This will drastically reduce the control of the vehicle.

Tires have special tread patterns that ensure optimum drainage of the water away from the tread surface. This effect does however reduce proportionally as speed increases.

The most effective protection is to adjust driving speeds to the weather conditions.

Balancing

At high speeds, tires generate enormous centrifugal forces. Even tiny irregularities in the tire of only a few grams are multiplied by many orders of size.

Such imbalance stresses tires and suspension. This weight irregularity can be tested and identified at in tire dealerships and is balanced by adding small counter-weights.

Every time a tire is fitted to a wheel, it should be balanced. Bead

The bead of the tire is that part which sits on the rim. At the center of the bead is the core, which comprises a bundle of steel wires embedded in rubber.

This provides a safe and solid seating of the tire on the rim. Braking distance

The distance required for braking depends on the speed of the vehicle, the condition of the road surface and the condition of the tires, in particular the tread. Check the tires tread depth regularly and change your tires when worn down to the "tread wear indicators" located at the bottom of the tread grooves.

Camber

The purpose of wheel camber is to reduce friction during cornering. The camber is measured when the wheels are standing on a flat surface. The difference from the vertical (inward or outward tilt of the tire) is then referred to as either positive or negative camber.

Casing

Modern tires are made of many different materials and components.

Looked at schematically, there is the outer cover - the tread and sidewall, and the substructure, the casing.

Casing components may include steel and/or textile cord plies, the inner liner (to make tube-less tires airtight), sidewalls, the apexes, the bead core (keeps the tire on the rim) and the bead reinforcement.

Chains

Even modern winter tires can sometimes not help when there are huge amounts of snow and steep gradients. In these situations traction, lateral control and reliable braking require tire chains. In order to be prepared it is recommended to try and fit chains in a "dry run".

Snow chains have to be draped over the drive wheels.

Please also note that a maximum speed is given. With some low profile tires a problem can result: the reduced space between the tires and the wheel arch leaves no room to fit snow chains.

Date of Manufacture

The date of manufacture of a tire is indicated on the tire's sidewall at the end of the DOT serial number.

Tire manufacturers have adopted a standard identification system: four numbers, which indicate the week and the year of manufacture. For example, the figures 0201 indicate that the tire was made in the second week of the year 2001.

Direction of Rotation

On standard tires with symmetrical tread patterns, it does not matter which way the tire is fitted on the rim and in which position it is fitted on the car.

Some tire manufacturers have, however, started producing tires with specific directions of rotation in order to improve wet grip and optimize noise generation.

The direction of rotation is marked on the side of the tire with an arrow. This side of the tire must be on the outside, and the tire must roll forwards in the direction of the arrow for optimum tire performance.

A number of tires with asymmetric tread patterns are also now available which do not have a specific direction of rotation.

DOT Serial Number

The "DOT" symbol certifies the tire manufacture's compliance with the U.S. Department of Transportation tire safety standards. The DOT serial number is located on the lower sidewall of the tire, on one side only. Below is a description of the serial number. Starting in the year 2000, four numbers are used for the Date of Manufacture, first two numbers identify the week and the last two numbers identify the year of manufacture. Prior to year 2000 three numbers are used for the Date of Manufacture, first two numbers identify the week and the last number identifies the year of manufacture. To identify tires manufactured in the 90's a decade symbol (a triangle on its side) is located at the end of the DOT serial number.

For Example: DOT NJ HR 2AE2 529529

Date of Manufacturer, example: 529 (52nd week of 1999) or 5200 (52nd week of 2000).

2AE2

Tire Type Code (coding for type of tire optional by manufacture).

HR

Tire Size Code Number.

NJ

Manufactures Plant Identification Code

DOT

Reference Symbol (certifies the tire manufactures compliance with U.S. Department of Transportation tire safety standards).

ESP / Electronic Stability Program

An Electronic Stability Program, ESP, helps master critical driving situations, for example when the vehicle suddenly over steers during cornering or when sudden evasive action is required. The systems detects skidding movements within fractions of a second and can take corrective action.

ESP systems not only function when road conditions are good, but also on wet, on icy and on unpaved roads.

Technically speaking, The ESP system combines the ABS / Anti-Lock Brake Block System, electronic braking pressure distribution, ASR /

Anti-slip-control and yaw control.

Emergency Mobility Systems

If a tire punctures and looses air, a standard size or a temporary special spare tire must be put on in order to continue the journey.

In order to avoid the troublesome, sometimes dangerous procedure of changing a tire on an open road, various manufacturers now offer so-called emergency mobility systems.

What these tires have in common is that when all air pressure is lost the rim does not destroy the tire. The journey can be continued without changing the tire - over a limited distance at a restricted speed.

Load Index, Ply Rating or Load Range

These symbols are found on the sidewall of the tire indicating the load - carrying capacity of the tire.

Mixing Tires

It is recommended that all four tires be of the same size, construction and speed rating. If tires of different speed rating are mounted on a vehicle, the vehicle speed capability will be limited to the lowest speed-rated tire on the vehicle. It is recommended that the lower speed-rated tires be placed on the front axle regardless which axel is driven. This should be done to prevent a potential oversteer condition. Vehicle handling may also be affected. Consult the tire manufacture.

Radial Tires

Radial tires have body cords that run across the tire nearly perpendicular to the beads. Radial tires have belt plies, which are laid diagonally under the tread to stabilize and strengthen the tread area. and add flexibility to the sidewall. By restricting tread movement during contact with the

road, the belt plies increase improve tread life, traction and improve handling.

Reinforced or XL (extra load) Tires

Reinforced or XL (extra load) tires are specially reinforced tires. They can carry higher loads than a tire of the same size.

Reinforced tires are designated on the Sidewall by the letters "RF", extra load tires with the letters "XL"

Reinforced and XL tires require need higher inflation pressures compared to standard tires.

Revolutions Per Mile (RPM)

The number of revolutions a tire makes in one mile, at a given load, speed and inflation. Sometimes called RPK or revolutions per kilometer.

Rolling Resistance

The drag force required to put a free rolling tire into motion. Tires are not rigid, but flexible. During driving the tires compress, and flex.

This flexing absorbs energy, converting it into heat.

In order to reduce rolling resistance, manufacturers use special rubber compounds. Any reduction in the rolling resistance of the tire helps reduce fuel consumption.

Since rolling resistance also increases with low Inflation pressure, it is beneficial to check the pressure of tires regularly.

Rotation

Refer to your Vehicle Owners Manual for recommended rotation pattern and interval for your vehicle. If not available, follow one of the patterns shown below. It is recommended to rotate your tires every 6,000 to 8,000 miles, or sooner if uneven treadwear begins to appear. The purpose for regular rotation is to achieve more uniform treadwear on all tires on your vehicle. If tires show uneven treadwear, ask the serviceperson to check and/or correct any alignment or other mechanical problem before rotation.

This is true for both front wheel and rear wheel drive vehicles. Full size spare spare tires should be included in the rotation pattern for your vehicle. Compact spares (temporary use spares) should not be included in the rotation pattern.

Speed Symbol

Speed ratings for tires are identified by means of a speed symbol shown on the sidewall of a tire. The maximum speed for these symbols in shown in the table. Although a tire may be speed rated, tire manufactures do not endorse the operation of any vehicle in an unsafe or unlawful manner. Furthermore, tire speed ratings do not imply that a vehicle can be safely driven at the maximum speed for which the tire is rated, particularly under adverse road and weather conditions or if the vehicle has unusual characteristics.

Speed ratings are based on laboratory tests which relate to performance in the road, but are not applicable if tires are underinflated, overloaded, worn out, damaged or altered.

Example: Tire size P215/60R15 H 185/65 R 15 H: the H indicates a maximum permitted speed of 130 MPH.

Temporary Spare Tires

Temporary spares are designed to carry the same load as the standard size tire on your vehicle and can be applied to any position. Maintain the proper inflation pressure as shown on the sidewall of the tire, it requires a higher inflation pressure than a standard size tire. Refer to the information on the sidewall of the tire for proper usage & speed restrictions. With such a tire, a vehicle may be operated until it is convenient to repair or replace the disabled tire. Have your standard tire repaired or replaced as soon as possible, then return the temporary spare to the trunk to conserve its useable tread life. The temporary tire can be worn down to the tread wear indicators, same as your standard tire. At such time the tire must be replaced.

Toe

The toe describes the distance between the centerlines of the tires on an axle. The toe setting can be adjusted on all cars.

Since most wheels tend to run towards the outside because of the camber, most cars are set with a slight positive toe-in. This means that the wheels are slightly closer together at the front than at the back.

Incorrect settings for your vehicle result in uneven tire wear. If you notice uneven tire wear, then have your vehicle alignment settings checked.

Tread

The tread is that part of the tire with the groove pattern which is in contact with the road. The tread is specifically design to provide traction for stopping, starting, cornering and provide long lasting wear.

Tread Depth

The measured distance from the tread surface to the bottom of the main grooves away from the Tread Wear Indicators. Usually specified in 1/32 of an inch.

TWI (tread wear indicator)

Tread wear indicators ("wear bars") are located at the base of the main grooves and are equally spaced around the tire. Always remove tires from service when they reach a remaining tread depth of two thirty-seconds of an inch (2/32"). If not corrected, wet weather accidents are more likely to happen due to skidding on bald or nearly bald tires. Also, excessively worn tires are more susceptible to damage from road hazards. Built-in treadwear indicators, or "wear bars," which look like narrow strips of smooth rubber across the tread, will appear on the tire when that point of wear is reached. When you see these wear bars, the tire is worn out and it's time to replace the tire.

Tire Size Designation

The dimensions of a tire are detailed on the sidewall.

In the case of a P185/65R 14 tire, the figures mean the following: 185 = width of tire in mm; 65 = the ratio of the height to the width as a percentage; R = radial construction; 14 = diameter of the rim in inches.

Tire Storage

Tires should be stored in a dry, cool place, away from sunlight and sources of ozone, such as electric motors.

If you must store tires flat, (one on top of the other), make sure you don't stack too many on top of each other. Too much weight can damage the bottom tire.

Also be sure to allow air to circulate around all sides of the tires, including underneath, to prevent moisture damage.

If storing tires outdoors, protect them with an opaque waterproof covering and elevate them from the ground. Do not store tires on or over black asphalt or other heat-absorbent or reflective surfaces, such as

snow-covered ground or sand. Solvents, fuels, lubricants and chemicals should be kept out of contact with tires.

Spare tire carriers on your vehicle are not intended to be used for long term tire storage. If your vehicle has a full size tire (same size and type tire recommended for use by the vehicle manufacture not temporary use spares) as a spare, it should be included in the tire rotation pattern.

UTQG (Uniform Tire Quality Grading)

Treadwear

The treadwear grade is a comparative rating based on the wear rate of the tire when tested under controlled conditions on a specified government test track. A tire graded 200 would wear twice as long on the government test course under specified test conditions as one graded 100. It is wrong to link treadwear grades with your projected tire mileage. The relative performance of tires depends upon the actual conditions of their use and may vary due to driving habits, service practices, differences in road characteristics and climate.

Traction

Traction grades, from highest to lowest, are AA, A, B and C. They represent the tire's ability to stop on wet pavement as measured under controlled conditions on specified government test surfaces of asphalt and concrete.

Temperature