INFORMATION PAGE


HEADING 1 - HOW TO READ A TRE


HEADING 2 - LEXICON

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HOW TO READ A TIRE

In addition to the tire brand and model, the sidewall always indicates the critical information regarding size and capacities.

Load and Speed Ratings

Load Speed
Load Rating Load Speed Rating Maximum Speed
Some Examples Q 160 km/h
74 375 kg S 180 km/h
76 400 kg T 190 km/h
80 450 kg H 210 km/h
84 500 kg V* More than 210 km/h
88 560 kg W 270 km/h
92 630 kg Y 300 km/h
96 710 kg Z* More than 240 km/h
100 800 kg
104 900 kg
108 1000 kg
112 1120 kg *The meaning of V and Z ratings may differ from one manufacturer to the other.

Additional info:

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LEXICON

A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

Alignment

Adjustment of all the wheels on the vehicle to make them point in the same optimum direction relative to the road and each other.

All-Season High-Performance Passenger Car Tire

Generally designed for luxury four-door sedans, this line of tires combines high-performance handling and a smooth, comfortable ride.

All-Season High-Performance Tire

Provides great traction in snow and on ice without sacrificing performance on a dry road.

All-Season Tire

Extremely dangerous situation where water accumulates in front of the tires, making them lose contact with the road surface. The vehicle then skims the surface of the water and loses control.

Bead

Section of the tire resting on the wheel. Inside is a hoop of steel wires, wrapped or reinforced by ply cords that firmly hold the tire unto the wheel's rim.

Belt

Layer of cords coated with rubber located between the plies and the tread. These cords are typically made of steel but can also be made of fibreglass, rayon, nylon, polyester or other fibres.

Carcass (or casing)

Tire's support structure made up of plies anchored in the bead of one side and anchoring itself according to a radius in the other side's bead.

Cold Inflation Pressure

Amount of air pressure in a tire, measured in pounds per square inch (psi) before the tire has built up heat from running.

Contact Surface

Point of contact between the tire and the road surface. Also called footprint.

Cornering Handling

The force exerted on tires during cornering-the ability of the tires to stick to the ground and resist lateral force-maintains the vehicle in the desired angle.

DOT Rating

Code moulded on the sidewall of a tire indicating that the tire complies with the U.S. Department of Transport safety standards for motor vehicles.

Dual Tires

Tires mounted side by side on an axle for the purpose of increasing the load and grip capacity; four tires on an axle.

Dynamic Balance

Exists when the weight is evenly spread both along the circumference and on each side of its longitudinal axis. A tire-wheel assembly out of its dynamic balance will produce fluttering of the wheels, or shimmy.

Extra Load

Tires that can support higher loads because their maximum inflation pressure is higher than the standard maximum.

Free Diameter

Diameter of the unloaded, inflated tire.

Groove

Space between two adjacent ribs.

Gum Compound

Combination of raw materials according to carefully established processes. Such compound is adapted according to the performance required for each type of tire.

Handling

Normal control of a vehicle by the driver.

High Floatation System for Light-Duty Trucks

Tires with lower sidewalls and wider tread designs providing better grip on surfaces like sand or off-road soft soil.

High-Performance Tire (or maximum performance/ultra-high performance)

Tire whose handling, traction and cornering grip are superior to standard tires. High-performance tires are also rated for running at higher speeds than other tires.

Inflation Pressure

Amount of air inside a tire exerting outward pressure on each square inch of tire; expressed in pounds per square inch (psi) or in kilopascals (kPa - metric designation for air pressure).

Kilopascal

The metric unit for inflation pressure. One psi (pound per square inch) equals 6.9 kPa.

Load Limit

Defines the maximum load a tire can carry with a determined inflation pressure.

Load Rating

Indicates the weight that the tire is certified being capable of supporting under maximum tire pressure. Number included between 0 and 279 corresponding to a tire's load capacity.

M+S, M/S or M&S

All-season rating for tires offering a certain degree of performance in mud and snow. Meets the standards of the Rubber Association of Canada regarding mud and snow tires.

Maximum Inflation Pressure

Maximum air pressure to which a cold tire may be inflated; moulded on the sidewall.

Normal Load

Weight the tire can support in accordance with its size and recommended tire inflation pressure.

Over-Inflation

Too much air in the tire, resulting in premature wear in the middle of the tread.

Passenger Car Tire

Typically boasts extended life, comfort and all-season traction.

Plus-Sizing

Option allowing drivers to customize their vehicles by mounting low-profile tires on wider rims of one or two inches in diameter, usually for enhancing vehicle performance, handling and appearance.

Ply

One of the rubber-coated layers making up the structure of a tire. Plies are typically reinforced by textile or steel cords.

Pneumatic Tire

Tire designed to be filled with air.

PSI

Abbreviation for pounds per square inch.

Pulling

When a vehicle veers toward one side independently of the steering wheel due to uneven wear of the tires, poor front- or rear-wheel alignment, worn or incorrectly adjusted brakes.

Radial Tire

Tire with plies arranged so that the cords in the carcass run at 90 degrees in relation to the longitudinal axis of the tread.

Rim

Part of the wheel onto which the tire is mounted.

Rim Border

Surface of the rim in contact with the bead's side.

Rim Diameter

Range of the rim's bead on which the tire rests.

Rim Width

Distance between the two opposite inside edges of the rim flanges.

Rolling Resistance

Force required to keep a tire moving at a consistent speed. The lower the rolling resistance, the less energy needed to keep a tire moving.

RPM (revolutions per minute)

Number of revolutions of a tire on a distance of 1 mile. May vary according to speed, load and inflation pressure.

Section Height

Height of the tire between the rim and outer tread.

Section Height with Load

Height of the tire section in contact with the road.

Section Width

Distance between a tire's outside sidewalls, excluding any lettering or other inscriptions.

Series

Tires with the same aspect ratio or same relationship between the section height and width.

Service Code

Digits and letters moulded on the sidewall indicating the load capacity, load rating, and speed at which a tire can carry a load in specific conditions. Also called load rating and speed rating.

Shoulder

The area where the sidewall and top meet.

Sidewall

Portion of the tire between the tread and the bead. Protects the tire against impacts. Contains important information about the tire.

Sipes

Special slits inside the design block that open up when the tire presses against the contact surface and close back to break water stress on the road and put the tread in contact with the road and maintain grip; improves grip on a wet or snow-covered surface.

Size

Includes tire width, composition, aspect ratio and rim dimensions.

Snow Tire (also called winter tire)

Tire whose tread design and rubber compound provide better traction in snow and on ice; identified by the inscription M+S, M&S or M/S on the sidewall. Quality snow tires display the RAC Mountain Snowflake symbol indicating that they meet the performance standards in snow as set by ACIC.

Speed Rating

Alphabetical code (A-Z) assigned to a tire indicating the range of speeds at which the tire can carry a load under specific service conditions.

Static Balance

When the weight mass is evenly spread around the axis of rotation. Vibrations in the seat, floor or steering column are signs of static unbalance.

Steering System

The entire mechanism that allows the driver to steer his vehicle; includes the steering wheel, steering column, steering gearbox, transmission and wheel supports.

Tensile Strength

Resistance of an object to stretching or breaking under the effect of stress. The metal belts of a tire are distinguished by their tensile strength.

Tire (or tyre)

Assembly of rubber, chemicals, fibres and metal, engineered with precision and designed to provide traction, cushion road shocks and carry a load under varying conditions.

Tire Designation

Alphanumeric code moulded on the tire's sidewall specifying the tire's size, including width, aspect ratio, rim diameter, load rating and speed rating. Most designations use the P-Metric system.

Tire Designation

Alphanumeric code moulded on the tire's sidewall specifying the tire's size, including width, aspect ratio, rim diameter, load rating and speed rating. Most designations use the P-Metric system.

Tread

Portion of the tire in contact with the road. It is distinguished by the design of its ribs and grooves. It provides grip under various conditions, resists violent forces, wear, friction and heat build-up.

Tread Depth

Depth of useable rubber, measured in .32 in. On a new tire of 10/32 in. of rubber, there is 8/32 in. of useable rubber. Tires should be replaced when the wear bars are visible at 2/32 in.

Tread Width

Portion of the tread design in contact with the road.

Tread Wear Indicators

Narrow strips, also called wear bars, that appear on the tread of the tire when only 2/32 inch of tread remains.

Tire Designation

Alphanumeric code moulded on the tire's sidewall specifying the tire's size, including width, aspect ratio, rim diameter, load rating and speed rating. Most designations use the P-Metric system.

Under-Inflation

Use of a tire without sufficient inflation pressure to support the weight of the vehicle with its occupants and the extra load; may cause tire rupture due to heat build-up inside the tire.

UTQGS (Uniform Tire Quality Grading Standards)

Tire information system issued by the US Government providing consumers with grades (AA to C) on tire traction and temperature. Life expectancy is usually graded between 60 and 700.

Wandering (steering instability)

Tendency of a vehicle to zigzag due to steering anomalies, worn tires, poor alignment, crosswinds or roadway unevenness.

Wheelbase

Difference in distance between the front and back of a pair of tires mounted on the same axle. Also, longitudinal distance of the centre of the front wheel to the centre of the back wheel on a vehicle's same side.

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