Tire Dictionary

• 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 Stem
• 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 your vehicle has been stopped for at least three hours and then driven less than one mile). Adjust to your vehicle manufacturers specified pressure while the tires are cold. Never reduce or bleed air pressure when tires are hot, as 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. Don't forget to check your standard size or temporary spare tire; your temporary spare 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.
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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. Also, your vehicle may need an alignment if your tires are wearing unevenly.
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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 (mud and snow). This meets the RMA (Rubber Manufacturers Association) 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 (below) next to the MS letters & are designed as winter tires. Tires designed for use in severe snow conditions will have tread patterns, structure and materials to give superior performance. These tires are marked with the "M+S" designation plus a mountain/snowflake symbol.

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ABS / Anti-Lock Brake System
An anti-lock braking system, or ABS is a safety system which prevents the wheels on a motor vehicle from locking up (or ceasing to rotate) while braking. A rotating road wheel allows the driver to maintain steering control under heavy braking by preventing a skid and allowing the wheel to continue interacting tractively with the road surface as directed by driver steering inputs. While ABS offers improved vehicle control, and may decrease stopping distances on dry and especially slippery surfaces, it can also increase braking distance on loose surfaces such as snow and gravel.
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ASR / Anti-slip-control
A traction control system (TCS), also known as Anti-Slip Regulation (ASR), is typically (but not necessarily) an electro-hydraulic system on production vehicles designed to prevent loss of traction of the driven road wheels, and therefore maintain the control of the vehicle when excessive throttle is applied by the driver and the condition of the road surface (due to varying factors) is unable to cope with the torque applied. Although similar to electronic stability control (ESC) systems, traction control systems do not have the same goal.
The intervention can consist of one or more of the following:
• Reduce fuel supply to one or more cylinders • Brake one or more wheels
• Retard or suppress the spark to one or more cylinders • Close the throttle, if the vehicle is fitted with drive by wire throttle
• In turbo-charged vehicles, the boost control solenoid can be actuated to reduce boost and therefore engine power
Typically, the traction control system shares the electro-hydraulic brake actuator (but does not use the conventional master cylinder and servo), and the wheel speed sensors with the anti-lock braking system.
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Aquaplaning
Hydroplaning or aquaplaning by the tires of a road vehicle occurs when a layer of water builds between the rubber tires of the vehicle and the road surface, leading to the loss of traction and thus preventing the vehicle from responding to control inputs such as steering, braking or accelerating. If it occurs along all four wheels, the vehicle becomes, in effect, an uncontrolled sled.
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Balancing
Tire balance, also referred to as tire unbalance or imbalance, describes the distribution of mass within an automobile tire and/or the wheel to which it is attached. When the tire rotates, asymmetries of mass cause the wheel to wobble for reasons discussed below. This wobbling can give rise to ride disturbances, usually vertical and lateral vibrations. The ride disturbance due to unbalance usually increases with speed. Vehicle suspensions can be excited by tire unbalance forces when the speed of the wheel reaches a point that its rotating frequency equals the suspension’s resonant frequency. Tires are inspected in factories and repair shops by two methods: static balancers and dynamic balancers. Tires with high unbalance forces are downgraded or rejected. When tires are fitted to wheels at the point of sale, they are measured again, and correction weights are applied to counteract the combined effect of the tire and wheel unbalance.
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Bead
Tire bead is the term for the edge of a tire that sits on the wheel. Wheels for automobiles are made with a small slot or groove for the tire bead to sit in. When the tire is properly inflated the air pressure within the tire keeps the bead in this groove. This provides a safe and solid seating of the tire on the rim.
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Braking Distance
Braking distance refers to the distance a vehicle will travel from the point where its brakes are fully applied to when it comes to a complete stop. It is affected by the original speed of the vehicle, the type of brake system in use and the coefficient of friction between its tires and the road surface. 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.
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Camber
Camber is the tilting of the wheels from the vertical when viewed from the front of the vehicle. When the wheels tilt outward at the top, the camber is positive (+). When the wheel tilts inward at the top, the camber is negative (-). The amount of tilt is measured in degrees from the vertical. Camber settings influence the directional control and the tire wear.
• Too much positive camber will result in premature wear on the outside of the tire and cause excessive wear on the suspension parts.
• Too much negative camber will result in premature wear on the inside of the tire and cause excessive wear on the suspension parts.
• Unequal side-to-side camber of 1° or more will cause the vehicle to pull or lead to the side with the most positive camber.
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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.
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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.
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Date of Manufacture
Automobile tires are described by an alphanumeric code, which is generally molded into the sidewall of the tire. This code specifies the dimensions of the tire, and some of its key limitations, such as load-bearing ability, and maximum speed. The date of manufacture of a tire is indicated on the 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.
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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. However, some tire manufacturers have 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.
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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 U2 H8 LMCR 1604 - 1604 Date of Manufacturer, example: 1604 (1st week of April 2004). U2H8 Tire Type Code (coding for type of tire optional by manufacture). H8 Tire Size Code
Number. U2 Manufactures Plant Identification Code DOT Reference Symbol (certifies the tire manufactures compliance with U.S. Department of Transportation tire safety standards).
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ESP / Electronic Stability Program
An Electronic Stability Program (ESP) - or Electronic stability control (ESC) is a computerized technology that improves the safety of a vehicle's stability by detecting and minimizing skids. When ESC detects loss of steering control, ESC automatically applies the brakes to help "steer" the vehicle where the driver intends to go. Braking is automatically applied to individual wheels, such as the outer front wheel to counter oversteer, or the inner rear wheel to counter understeer. Some ESC systems also reduce engine power until control is regained. Electronic stability control does not improve a vehicle's cornering performance; rather it helps to minimize a loss of control. In the United States, NHTSA estimates 5,300-9,600 traffic fatalities could be avoided if all passenger vehicles were equipped with the feature. According to the IIHS one-third of fatal accidents could be prevented by the technology.
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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.
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Load Index, Ply Rating or Load Range
The load range or ply rating branded on a tire's sidewall helps identify its strength and ability to contain air pressure. While specific load ranges are assigned to passenger tires, load ranges are identified in ascending alphabetical order for light truck tires (the further along the letter is in the alphabet, the stronger the tire and the greater amount of air pressure it can withstand and load it can carry). Before load ranges were adopted, ply ratings were used to identify the relative strength of light truck tires with higher numerical values assigned to tires featuring stronger, heavier duty constructions.
Today's load range/ply ratings do not count the actual number of body ply layers found inside the tire, but indicate an equivalent strength based on early bias ply tires. Most radial passenger tires have one or two body plies, and light truck tires, even those with heavy duty ratings (10-, 12- or 14-ply rated), actually have only two or three fabric body plies, or one steel ply.

Load Range and Load Pressure for Passenger Tires
Load Range Load Pressure (psi)
P-metric Light Load
Standard Load
Extra Load
35
35
41
Euro-metric Standard
Reinforced/Extra Load
36
42

Load Range, Ply Rating and Load Pressure for Light Truck Tires
Load Range Ply Rating Load Pressure (psi)
LT-metric B 4 35
LT-numeric C 6 50
Flotation LT* D
E
F
8
10
12
65
80
95
*Selected large Flotation LT sized tires have reduced load pressures from the values shown above.

Load Range, Ply Rating and Load Pressure for Light Truck Tires
Load Range Ply Rating Load Pressure (psi)
ST-metric B
C
D
4
6
8
35
50
65

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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.
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Radial Tires
Tires are not fabricated just from rubber. They would be far too flexible and weak. Within the rubber are a series of plies of cord that act as reinforcement. All common tires (since at least the 1960s) are made of layers of rubber and cords of polyester, steel, and/or other textile materials. This network of cords that gives the tire strength and shape is called the carcass. Radial tires lay all of the cord plies at 90 degrees to the direction of travel (that is, across the tire from lip to lip). This design avoids having the plies rub against each other as the tire flexes, reducing the rolling friction of the tire. This allows vehicles with radial tires to achieve better fuel economy than vehicles with bias-ply tires. It also accounts for the slightly "low on air" (bulging) look that radial tire sidewalls have, especially when compared to bias-ply tires. Interestingly the steel wire in radial car tires becomes magnetic so that when the tire rotates you get an alternating magnetic field. It is quite measurable with an EMF meter close to the wheel well when the car is moving and is a spectrum of harmonic strengths from 10 to several hundred Hertz.

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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 higher inflation pressures compared to standard tires.
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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.
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Rolling Resistance
Rolling resistance, sometimes called rolling friction or rolling drag, is the resistance that occurs when a round object such as a ball or tire rolls on a flat surface. It is caused mainly by the deformation of the object, the deformation of the surface, or both. Additional contributing factors include wheel radius, forward speed, surface adhesion, and relative micro-sliding between the surfaces of contact. It depends very much on the material of the wheel or tire and the sort of ground.
For example, rubber will give a bigger rolling resistance than steel. Also, sand on the ground will give more rolling resistance than concrete. A moving wheeled vehicle will gradually slow down due to rolling resistance including that of the bearings, but a train car with steel wheels running on steel rails will roll farther than a bus of the same mass with rubber tires running on tarmac. The coefficient of rolling resistance is generally much smaller for tires or balls than the coefficient of sliding friction.
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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 to the right.
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 service person 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.

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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 P195/55R16 85H
• P - these tires are for a passenger vehicle. However 'P' denotes P metric size load & speed    rating changes for P tire & non- P tires
• 195 - the nominal width of the tire is approximately 195 mm at the widest point
• 55 - indicates that the height of the sidewall of the tire is 55% of the width (107 mm)
• R - this is a radial tire
• 16 - this tire fits 16 inch diameter wheels
• 85 - the load index, a maximum of 515 kg per tire in this case
• H - the speed index, this means the maximum permitted speed, here 210 km/h (130 mph)

Example: 37X12.5R17LT
• 37 - the tire is 37 inches in diameter
• 12.5 - the tire has a cross section of 12.5 inches
• R - this is a radial tire
• 17 - this tire fits 17 inch diameter wheels
• LT - this is a light truck tire
Speed rating
Code mph km/h Code mph km/h
A1 3 5 L 75 120
A2 6 10 M 81 130
A3 9 15 N 87 140
A4 12 20 P 94 150
A5 16 25 Q 100 160
A6 19 30 R 106 170
A7 22 35 S 112 180
A8 25 40 T 118 190
B 31 50 U 124 200
C 37 60 H 130 210
D 40 65 V 149 240
E 43 70 Z over 149 over 240
F 50 80 W 168 270
G 56 90 (W) over 168 over 270
J 62 100 Y 186 300
K 68 110 (Y) over 186 over 300
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Temporary Spare Tires
Compact temporary spare tires are physically shorter and narrower than the vehicle's standard tires and wheels. Their smaller dimensions require they operate at higher inflation pressures than standard tires (typically 60 psi). Compact temporary spares also feature lighter-weight construction and a shallower tread depth than standard tires to reduce vehicle weight, as well as allow more trunk space to be dedicated to luggage. The compact temporary spare tire and wheel that comes with a vehicle is designed to fit that vehicle only. Never attempt to use a temporary spare and wheel on another vehicle unless it is the exact same make and model. Temporary spares are designed to carry the same load as the standard size tire on your vehicle and can be applied to any position. 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.
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Toe
In automotive engineering, toe is the symmetric angle that each wheel makes with the longitudinal axis of the vehicle, as a function of static geometry, and kinematic and compliant effects. This can be contrasted with steer, which is the antisymmetric angle, i.e. both wheels point to the left or right, in parallel (roughly). Positive toe, or toe in, is the front of the wheel pointing in towards the centreline of the vehicle. Negative toe, or toe out, is the front of the wheel pointing away from the centreline of the vehicle. Toe can be measured in linear units, at the front of the tire, or as an angular deflection.

In a rear wheel drive car, increased front toe in (i.e. the fronts of the front wheels are closer together than the backs of the front wheels) provides greater straight-line stability at the cost of some sluggishness of turning response, as well as a little more tire wear as they are now driving a bit sideways. On front wheel drive cars, the situation is more complex.

Toe is always adjustable in production automobiles, even though caster angle and camber angle are often not adjustable. Maintenance of front end alignment, which used to involve all three adjustments, currently involves only setting the toe; in most cases, even for a car in which caster or camber are adjustable, only the toe will need adjustment.

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Tread
The tread of a tire or track refers to the rubber on its circumference that makes contact with the road. As tires are used, the tread is worn off limiting their effectiveness in providing traction. A worn tire tread can be replaced using a process known as retreading. The word tread is often used incorrectly to refer to the pattern of grooves cut into the rubber. Those grooves are correctly called the tread pattern, or simply pattern.
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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.

According to most states' laws, tires are legally worn out when they have worn down to 2/32" of remaining tread depth. To help warn drivers that their tires have reached that point, tires sold in North America are required to have indicators molded into their tread design called "wear bars" which run across their tread pattern from their outside shoulder to inside shoulder. Wear bars are designed to visually connect the elements of the tire's tread pattern and warn drivers when their tires no longer meet minimum tread depth requirements.
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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.
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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.

Size
There is a lot of useful information molded into the sidewall of every tire. Included are manufacturer and tire name; section width; aspect ratio; construction; rim diameter; speed rating; load range; treadwear, temperature and traction labeling and other required designations.

All tires sold in the United States must meet the size standards for bead shape, width, diameter and other parameters established by a recognized standardizing organization. World leaders among such organizations are the European Tire and Rim Technical Organization (ETRTO) and the U. S. Tire and Rim Association (T&RA). Both use a partially metric-based system. Virtually all passenger tires on the market today use the rim and tire sizing, load and inflation system established by these bodies. All U. S. highway tires must also meet U. S. D.O.T. standards as indicated by the letters 'D.O.T.' on the sidewall.

The several tire size designations in use today depend on when a vehicle was manufactured and whether it was domestically produced or imported. All tire-sizing systems used today provide information about a tire's dimensions.
Among the most important for proper fitment is height, width and load carrying capacity. P-Metric: This is the United States version of a metric sizing system established in 1976. P-Metric passenger car tire sizes begin with "P," which simply means "Passenger."

Metric: This European tire sizing system is similar to P-Metric but does not use the "P" designator.

Alphanumeric: This system was established in 1968 and is based on the tire's load carrying capacity, correlated to its overall size. The tire's capacity and size are indicated by letter designations from "A" (smallest tire, lowest capacity) to "N" (largest tire, highest capacity). An example of an Alphanumeric tire size is BR78-13. "B" shows size/load, "R" indicates radial construction, "78" is the aspect ratio, and "13" is the wheel size in inches.

Numeric: This is the oldest standardized tire sizing system for passenger car tires. When this system was adopted, tire aspect ratios were either 92 or 82. For example, a 7.00-14 tire has a section width of 7 inches, a rim diameter of 14 inches and an aspect ratio of 92. The low profile equivalent size tire with an aspect ratio of 82 would be 7.35-14 (Example: P215/65R15 89H).

P Passenger (P-Metric / Non-P-Metric)
This indicates a passenger car tire. If the first character in the size designation is a "P," the tire is a "P-Metric" tire and is engineered to standards set by the T&RA. If there is no "P", the tire is engineered to ETRTO standards and is a metric tire. The standards set by T&RA and ETRTO have evolved together and are virtually interchangeable.

215 Section Width
These numerals indicate the tire section width in millimeters. This is the dimension from sidewall to sidewall. A tire's section width will vary depending on the rim to which it is fitted. The section width will be larger on a wide rim and smaller on a narrow rim. Therefore, each tire is measured to specific rim width. (To convert millimeters into inches, divide by 25.4.)

65 Aspect Ratio
This two-digit number indicates the tire's aspect ratio. It compares the tire's inflated section height, which is the distance from the bead to the tread, to its section width (maximum). An aspect ratio of 65 means that the tire's section height is 65% of the tire's section width. For clarity, the section width in millimeters is separated from the aspect ratio by a slash (/).

R Construction
This letter indicates the type of ply construction in the tire's casing or carcass. "R" means radial. "D" means diagonal, referring to bias ply tires. "B" means belted for belted-bias ply tires. Never mix radial tires with any other construction on a car.

15 Rim Diameter
The "15" indicates the rim diameter in inches. It is the diameter of the tire bead seat ledge in the rim. Most tires are built to inch standards for rim diameters. However, some tires are built to millimetric rim dimensions. Always match the tire's rim diameter to the wheel rim diameter. This is important for safety. NOTE: A millimetric rim has a different shape than an inch rim; they are not interchangeable.

89H Service Description
The service description is an alphanumeric combination, consisting of two parts, a number and a letter. In this example, "89" is the load index, which represents the load carrying capacity. (All passenger car tires in the U.S. are also marked with their actual load limit in pounds.) The letter part is the speed symbol, 'H,' in this example. This is the maximum speed for which the tire is rated at the load specified by the load index. In this example, 'H' means speeds up to 130 mph. Dunlop does not recommend the use of any of its products in excess of legal speed limits. Speed Ratings do not necessarily imply that the performance (handling and grip) of the tire meet the performance standards implied by the ratings.

Tire speed ratings must exceed the maximum speed capability of the vehicle to which they are fitted. Not all tires sold in the U.S. are speed rated, although many modern performance and luxury cars are equipped with speed rated Original Equipment tires. It is important to remember this when replacing the tires on your vehicle. Replace tires with equivalent or higher speed rated tires. Do not downgrade speed ratings from Original Equipment ratings.

NOTE: Speed Ratings - where applied are indicative of high performance characteristics based on European ECE 30 Indoor Wheel testing and are not valid for damaged, altered, repaired, under-inflated, overloaded, excessively worn, or re-treaded tires. We do not recommend the use of any product in excess of legal speed limits.

Service Indicators
Some tires carry additional markings related to service. An M&S or M+S designation means the tire is rated suitable by the manufacturer for mud and snow use. The guidelines are set by the Rubber Manufacturers Association (RMA) in the United States.

All-Season Designation
This is a marking which means that the tire meets M&S/M+S requirements without the drawbacks of noise and rolling resistance
associated with the traditional deep-lug winter tires. The M&S/M+S designation means that the tire is suitable for normal all-weather driving applications. Tires that meet the requirements of the M&S designation have better winter traction compared to those without the M&S symbol.

North American tire manufacturers and the RMA have established a voluntary, industry-wide definition for passenger and light truck tires intended for use in SEVERE SNOW CONDITIONS. Tires must meet a performance-based criteria featuring tread pattern, construction elements and materials which generally provide snow performance superior to that of tires bearing the RMA current M&S Rating. Such tires will display a mountain/snowflake symbol.

D.O.T.
The 10 digit D.O.T. code number molded into the sidewall designates the manufacturer and plant where the tire was produced, the tire line and size, and the week and year the tire was manufactured.

Maximum Pressure / Load
All passenger tires are marked on the sidewalls to indicate maximum load capacity and maximum inflation pressure. Truck tires will indicate recommended pressure for maximum loads for both dual and single application.

Harmonic Markings
Red dots on Dunlop high performance tires for match mounting purposes. These dots mark the 'high spot' of the tire, which is then matched with the 'low spot' on the rim to cancel out harmonic vibration.

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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.
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UTQG (Uniform Tire Quality Grading)
The UTQG rating is made up of three components:
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 an oversimplification to assume treadwear grades will be proportional directly to your actual 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. The testing does not take into account cornering, hydroplaning or acceleration.
Temperature
The temperature grades, from highest to lowest, are A, B and C. These represent the tire's resistance to the generation of heat.
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Valve Stem
Schrader valves (also called American valves) consist of a valve stem into which a poppet valve is threaded with a spring attached. They are used on virtually all automobile tires. The valve, fitted in the wheel, ensures that the tire can be filled with air. The correct valve is required for the correct wheel/tire assembly, this is the job of the tire dealer. The cause of a slow loss of air pressure can be a defective valve. The valve cap should always be fitted to the valve in order to protect the valve core from dirt and moisture.
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Valve Cap
The valve cap, although small, has a very important job: it protects the sensitive valve internals from dust, dirt and humidity. If valve caps are lost they should be replaced immediately in order to avoid expensive damage later.
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Winter Tires
Snow tires (winter tires) are tires designed for use in winter conditions, such as snow and ice. They are an alternative to the use of snow chains. Winter tires are generally tires with a different rubber composition from all-weather tires. The rubber in winter tires is softer, which means that it will provide better traction at lower temperatures. Winter tires provide more small-tread areas, allowing for more traction on snow; and in wet conditions allowing water to escape from under the tire more easily. This reduces the risk of aquaplaning. Winter tires won't prevent skidding on ice and snow, but greatly reduce the risk. In snowy areas, many cities and counties have "snow emergency" regulations which are invoked during heavy snowfalls. Check with authorities for the rules in your area. Under some rules, motorists are subject to fines if they block traffic and do not have winter tires on their vehicles. You can avoid this by equipping your vehicle with winter tires marked with "MS," "M&S," or "M + S" on the sidewall and severe snow marking.
If you change to winter tires, be sure they are the same size and construction type as the other tires on the vehicle. It is recommended that winter tires be applied on all four positions. It is acceptable to install winter tires only on the rear position of a rear wheel drive vehicle. If winter tires are installed on the front position of any vehicle, the MUST also be installed on the rear position. Without winter tires on the rear, vehicle handling can be adversely affected and may result in loss of vehicle control which could cause serious injury or death. If winter tires with a lower speed rating than listed on the vehicle placard are installed for use in winter conditions, the speed capability of the vehicle is reduced to the speed rating of the winter tires.
In areas where heavy snowfalls are frequent, many drivers carry chains for use in emergencies, or have their tire dealer apply studded winter tires or install tires for use in severe snow conditions. Most states have time limits on the use of studs. Before installing studded tires, check the regulations in your area. If studded tires are applied to the front axle, they also must be applied to the rear axle. If you use chains, make sure they are the proper size and type for your tires, otherwise they may damage the tire sidewall and cause tire failure. 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.
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