Tire Glossary | Costco Tires (2024)

ABRASION:

Wearing away by scraping, rubbing or impact. The progressive wearing away of a tire in service.

AGING:

Deterioration of physical and chemical properties of rubber by oxidation over a period of time.

AIR PRESSURE:

The amount of air inside the tire pressing outward on each square inch of tire; expressed in pounds per square inch (psi) or kiloPascals (kPa), the metric designation for air pressure (6.9 kPa = 1 psi).

ALIGNMENT:

The state in which all wheels on a vehicle are pointed in the optimum direction relative to the road and each other.

ALL-SEASON TIRE:

A tire with a tread design and tread compound that gives better traction in mud and/or snow. A tire that is designated All Season must meet specified RMA (Rubber Manufacturers Association) criteria. All Season tires carry one of the following designations on the sidewall M+S, M&S, or M/S.

ALPHA NUMERIC:

A term for describing the size of a tire in which both letters of the alphabet and numbers are used.

ANTI-OZONANT:

A substance added to rubber to delay aging due to ozone.

ANTI-OXIDANT:

A substance added to rubber to delay aging by oxidation.

ARAMID:

A synthetic fabric used in some tires that is (pound-for-pound) stronger than steel.

ASPECT RATIO:

The relationship of a tires section height to its section width, expressed as a number that represents the nominal percent the tires section height is of its section width. Section Height Section Width x 100

BALANCE:

The state in which a tire and wheel spin with all their weight distributed equally.

BEAD:

A round hoop of steel wires that is shaped to fit the rim around which the tires body plies are wrapped and which serves to hold the tire onto the rim.

BELT:

A rubber-coated layer of cords that is located between the body plies and the tread rubber. Cords may be made from steel, fibreglass, rayon, nylon, polyester or other fabrics.

BELTED BIAS TIRE:

A pneumatic tire with a body similar to that of bias ply tires, but which also includes two or more belts under the tread.

BIAS PLY TIRE:

A pneumatic tire in which the plies are laid at alternate angles less than 90 degrees to the center line of the tread. Plies usually run at angles of about 30-40 degrees relative to the tire centerline in a criss-cross fashion.

BLEEDING A TIRE:

Releasing air to reduce pressure in tire.

BLEMISH:

Surface irregularity or imperfection.

BLISTER:

A separation within sidewall or liner stock, or a separation between sidewall carcass or liner and carcass.

BODY:

Tire structure excepting tread and sidewall rubber.

BOTTOMING (BY A VEHICLE):

Condition in which the suspended body and frame hit together because of weak shock absorbers.

BRUISE:

An injury to a tire, weakening, breaking or separating cords in the carcass without cutting or tearing of surface rubber.

CAMBER:

Inward or outward tilt of front wheels; inwards at top is negative camber. Under the condition known as positive camber both wheels slant inward at the bottom. Under this condition wheels will roll freely, but excessive wear will be produced on the outer shoulder of the tire tread. Steering and control will be difficult.

CARBON BLACK:

A general name for various forms of carbon, used as compounding ingredients in rubber.

CARCASS:

The tire body beneath the tread and sidewalls; also called casing.

CARRYING CAPACITY:

Maximum rated tire load as established by the Tire and Rim Association.

CASING:

See Carcass.

CASTER:

Backward or forward placement of an axle, locating center of weight ahead or behind the ground contact point of wheel. Caster determines ease of steering and stability at high speeds. In passenger cars, caster is determined by the relative position of the upper ball joint (forward or rearward) in relation to the lower ball joint and is measured in degrees.

CHECKING:

Minute cracking in surface of rubber caused by aging and oxidation.

CHUNKING:

Tearing or breaking away pieces of tread rubber.

CIRCUMFRENTIAL CRACKS:

Cracks in a tire running parallel to beads. Usually consists of cracks in the grooves of the tread.

COLD INFLATION PRESSURE:

The amount of air pressure in a tire, measured at ambient temperature before a tire has built up heat from driving.

COMFORT:

Indicates the tires ability to minimize road noise, harshness, and vibration as perceived by the vehicle occupants.

CORD:

The strands of material forming the body plies or belt plies of the tire. Cords may be made from aramid, fibreglass, rayon, nylon, polyester or steel.

CRACKING-TREAD OR GROOVE:

Splitting in grooves caused by excessive strain.

CROSS-SECTION SIZE:

External sidewall-to-sidewall measure of tire exclusive of ribs. Also called Section Width.

CROWN:

Section between shoulders of the tires.

CROWN RADIUS:

The measurement of the curvature of a tire tread between the shoulders of the tire. Expressed as a percentage, it indicates the relative flatness of the tire tread area.

CURB SCUFFING:

Abrasion of shoulder and sidewall of tire caused by rubbing against curb as in parking.

CURING:

Process of heating or otherwise treating a rubber or plastic compound to convert it from a thermoplastic or fluid material into the solid, relatively heat-insensitive state desired in the commercial product. When heating is employed, the process is called vulcanization.

DEFLECTION:

A tire's free radius minus its loaded radius.

D.O.T.:

Department of Transportation.

DOT NUMBER:

A code molded into the sidewall of a tire signifying that the tire complies with U.S. Department of Transportation safety standards. The DOT code includes an alphanumeric designator, which can also identify the tires manufacturer, production plant, and date of production and brand.

DIRECTIONAL TREAD:

Tread design in which performance is dependent upon direction of rotation.

DUAL KISSING:

The intermittent contact of tires in dual as they flex due to inadequate dual spacing or overload.

DUAL SPACING:

A measurement, in inches, from the center of the tread of one tire to the center of the tread of the other tire in dual which provides clearance between duals for air circulation.

DUROMOTER:

A device to measure the hardness of rubber. The term is also applied to the readings obtained with this device: for example, a tire tread may be defined as 60 durometer, which means that it shows this degree of hardness when tested with the durometer.

DYNAMIC BALANCE:

Balancing of tire while rotating.

FEATHER EDGE:

Sharp, knifelike feathering along one edge of rib or blocks, due to scrubbing action of misaligned wheel on road.

FLANGE:

Vertical collar of rim which retains outer edges of beads.

FLAP:

A rubber protector used in tube type tires to prevent injury to the tube by the bead toes and at the valve slot of the rim.

FLAT SPOT:

Irregular wear in an isolated spot or spots around the tire tread. Flat spotting can also result from abrasion of the tire resulting from brake lock.

FLAT TREAD PROFILE:

Tread with very slight curve from shoulder to shoulder.

FLEXING:

Repeated bending from original shape.

FLEXING LINE:

Circumferential line in tire where maximum bending or flexing occurs.

FLOTATION:

Ability of a tire to support a load on soft, yielding terrain.

FOOTPRINT:

That portion of the tread in contact with the road.

FREE RADIUS:

The radius of the tire/wheel assembly that is not deflected under load.

FRICTION:

The force between the tires and the road surface which causes the tire to grip the road.

FRONT WHEEL SHIMMY:

Abnormal side-to-side vibration of front wheels.

FRONT WHEEL TRAMP:

Abnormal up-and-down vibration of front wheels mostly at high speeds.

GOUGING:

Chisel-like action of rocks or stubble on tires.

GROOVE:

The space between two adjacent tread ribs or blocks; also called tread grooves.

HANDLING:

Tire performance and "grip" on the road.

HARSHNESS:

In tire testing on an automobile, the degree to which small road irregularities are absorbed by the tires. An improvement in harshness is apparent to the driver by a reduction in the shocks or vibrations transmitted to him.

HEAT BUILD-UP (TIRE):

Increase in heat of tire while in use in excess of heat dissipated.

HEAT DISSIPATION (TIRE):

Removal of heat from a tire by conduction, convection and radiation from the surface.

HEEL AND TOE WEAR:

Sloping wear between ends of some tread elements (ripsaw-toothlike) shifting movement of tread units in contact with road.

HIGHWAY TIRES:

Also called summer tires; designed for wet-and-dry weather driving, but not for use on snow and ice.

HYDROPLANING:

A skimming effect caused by tires losing contact with a surface covered with water when travelling at speed.

IMPACT BREAK:

Rupture in tire carcass due to sudden shock.

IMPACT RESISTANCE:

Ability of tire to withstand injury from sudden shock.

INNERLINER:

The innermost layer of a tubeless tire. The innerliner prevents air from permeating through the tire.

KILOPASCAL:

(kPa) The metric unit for air pressure. There are 6.9 kPas to one psi.

LINER:

(SEE INNER LINER)

LOAD CARRYING CAPACITY:

Maximum load for which tire is designed under standard conditions.

LOADED RADIUS:

Distance from wheel axis of rotation to supporting surface at a given load and stated inflation pressure.

LOADED SECTION HEIGHT:

The loaded radius minus half of the nominal rim diameter. Distance from rim seat to outer tread surface of a loaded tire.

LOAD INDEX:

An assigned number ranging from 0 to 279 that corresponds to the load carrying capacity of a tire.

LOAD RANGE:

A system of designations which identifies the carrying capacity range of a tire. These markings shown on the tire indicate the ply rating established for the tire. Passenger tire designations are B (4-ply rating), C (6-ply rating), and D (8-ply rating).

LOW PROFILE TIRE:

A tire in which the cross-section has a squat appearance. Low profile refers to the fact that the tire's cross-section height is less than 80% -85% of the section width.

MAXIMUM INFLATION PRESSURE:

The maximum air pressure to which a cold tire may be inflated; found molded onto the sidewall.

MAXIMUM OVER-ALL TIRE WIDTH:

Maximum outside cross-sectional width of inflated tire without load, including sidewall, rib, and decorations.

MAXIMUM RATED LOAD:

Greatest load for which vehicle or tire is built.

MISALIGNMENT:

Maladjustment of one or more parts of steering mechanism, causing unsatisfactory operation of wheels and vehicle.

MOLD:

The heated cavity in which tires are vulcanized.

MONO-PLY TIRE:

A tire made with only one casing ply.

MSRP:

Manufacturers Suggested Retail Price. Actual retail prices may vary. Please contact your nearest dealers for pricing in your area.

MUD-TRACTION:

Tire performance in mud.

NOMINAL RIM DIAMETER:

The diameter of rim seat supporting the tire bead. Examples 13", 15" and 16.5". This measurement is taken where the tire seats on the rim.

NON-DIRECTIONAL TREAD:

Tread design which is equally effective in either direction of rotation.

N.T.D.R.A.:

National Tire Dealers and Retreaders Association.

OFF-ROAD TRACTION:

Indicates the tires ability to provide grip and traction for starts and stops in off-road conditions such as mud, turf, etc.

ORIGINAL EQUIPMENT(OE):

Refers to tires sold to vehicle manufacturers for use in equipping their manufactured units. The tire size recommended by the vehicle manufacturer.

OVERALL DIAMETER:

The outside diameter of the inflated tire, without any load.

OVERALL SCORE:

A summary based on a weighted average of how industry experts feel each tire would perform in individual attribute tests. These attributes were determined by a third-party industry-wide survey.

OVERALL WIDTH:

The distance between the outside of the two sidewalls, including lettering and designs.

OVER-INFLATION:

Tire inflation above recommended pressure.

OVER DEFECTION:

Excessive tire bending or distortion, due to too great load or insufficient air pressure (or both).

OVERLOAD:

A tire that is carrying weight that exceeds its rated capacity relative to its inflation pressure.

OVERSIZING:

Mounting larger tires than size specified for a vehicle to support heavier loads or provide increased flotation.

OVERSTEER:

The tendency of a vehicle to steer into a sharper turn than the driver intends, sometimes with a thrusting of the rear of the vehicle to the outside. Example a vehicle is said to have an oversteer condition during a turn when the rear tires have less grip on the driving service than the front tires have. The tendency is for the rear of the vehicle to slide out toward the outside of the turn. Oversteer is also referred to by the term Loose.

OZONE-03:

A form of oxygen molecules produced by electricity. Accelerates aging in tires.

OZONE CHECKING:

Formation of fine cracks in surface of rubber due to ozone in air.

PERFORMANCE HANDLING:

Indicates the extent to which the tire provides sharp response, strong dry traction, and well-balanced cornering grip to enhance a vehicles behavior in spirited driving.

PINNED:

A term which describes a tire that has small holes drilled into it to accommodate studs.

PLUG REPAIR:

The filling of nail hole by forcing repair material into the damaged area to fill it, often while the tire is mounted and containing air. This form of repair is not satisfactory.

PLUS-SIZING:

An option allowing drivers to customize their vehicle by mounting low-profile tires on wider rims of greater diameter, usually enhancing vehicle appearance, handling and performance.

PLUS O:

This term refers to replacing the original equipment tire with a wider and proportionately lower tire, without changing the wheels. Typically, this is the least expensive way to improve the look and handling of your car.

PLUS 1:

This fitment involves changing your tires and wheels. The "1" in "Plus 1" refers to fitting a wheel with a nominal rim diameter code one larger than the original. In this fitment, the proper tire will have a lower-aspect sidewall and may be wider. For example, you might go from an original tire of 185/70R14 to a 195/60R15 tire on a 15-inch rim diameter code.

PLUS 2:

This is a more exotic fitment, as it involves changing from your original size wheels to wheels having a nominal rim diameter two codes larger. Again, the tire will have a lower sidewall and may be wider.

PLY:

A rubber coated layer of fabric containing cords that run parallel to each other; extends from bead to bead and is located between the inner liner and belts or tread.

PLY RATING:

Strength of tire in terms of cotton ply strength. It need not indicate actual number of plies.

P-METRIC:

Uniform designation of tire sizes, in metric measurements originally introduced by American tire manufacturers in 1977; commonly called "P-metric series." A typical P-metric tire is P205/70R14 93S.

PNEUMATIC TIRE:

A tire filled with air (see Tire).

PRESSURE BUILD UP:

Increase of air pressure in tire caused by temperature rise of tire.

PRIVATE BRAND:

A special line of tires or tubes manufactured for and to the specifications of a private buyer.

PROFILE:

Shoulder-to-shoulder arc of tread cross-section.

PSI:

An abbreviation for pounds per square inch (psi). The amount of air inside a tire pressing outward on each square inch of tire is usually expressed in psi. Example: Front: 30 PSI Rear: 30 PSI. "It is important to have the proper air pressure in your tires, as under-inflation is the leading cause of tire failure. The correct air pressure for the tires on your vehicle is specified by the vehicle manufacture and is shown on the vehicle door edge, door post, glove box door, fuel door, or refer to your vehicle owner's manual."

PUNCTURE:

Any penetration of a tires air chamber by a foreign object, nail, glass, etc. resulting in the loss of air. Such loss can be rapid with the collapse of the innertube.

QUIET RIDE:

Tire performance with little or no noise.

RADIAL CRACKING:

Surface openings, generally in shoulder or sidewall of tire, running parallel to tire radius.

RADIAL PLY TIRE:

A type of tire with plies arranged so cords in the body run at 90-degree angles to the centerline of the tread.

RADIAL RUNOUT:

In tires, a measure of out-of-roundness; tested by rotating the inflated tire and measuring how far the surface of the tread varies from a true circle.

RAPID AIR LOSS:

Instantaneous rupturing of tire body, causing complete loss of air pressure.

RATED LOAD:

The maximum allowable load for a particular size and load range tire.

REPLACEMENT TIRE:

Any tire other than those sold as original equipment.

• RETAIL PRICE TIERS:
• Premium: the highest retail price tier of a common category of products
• Moderate: the mid-price tier of a common category of products
• Economy: the lowest retail price tier of a common category of products

REVERSION:

Excessive heating of a cured tire compound leading to deterioration of its physical properties.

REVOLUTIONS PER MILE(RPM):

Measured number of revolutions for a tire travelling one mile. This can vary with load and inflation.

RIB:

Tread section running circumferentially around a tire.

RIM:

A metal support for a tubeless tire or a tire and tube assembly upon which the tire beads are seated.

RIM BRUISE:

Damage caused when a tire hits an obstruction with sufficient force to compress the tire between rim flange and object.

RIM DIAMETER(NOMINAL OR BEAD SEAT):

Approximate diameter of the rim measured at the bottom of the flange (nominal). Bead seat diameter is the distance between intersections of bead seat line and heel line extended. True for passenger tires and most truck tires.

RIM PROTECTOR:

Raised sidewall rib to protect sidewall from curb scuffing. Also called buffing rib or scuffing rib.

RIM SEAT OR RIM FLANGE:

The curved metal extremes of a rim that retain the tire on the rim base.

RIM WIDTH:

Distance between the two inside flanges of the rim (where the tire seats).

R.M.A.:

Rubber Manufacturers Association

ROAD HAZARD:

Injury to a tire sustained in normal operation.

ROAD SHOCK:

Impact of road irregularities transmitted through tires to vehicle.

ROCK/STONE DRILLING:

A condition in which a rock has penetrated the tread rubber or fabric of a tire. Caused by the failure of tires to eject the rocks picked up by the grooves.

ROLLING:

The linear distance traveled by a tire in one revolution. This can vary with load and inflation. Rolling circumference can be calculated as follows: 63,360 divided by revolutions per mile = rolling circumference in inches.

ROLLING RADIUS:

Distance from axle to road under any given condition of load, speed or inflation.

ROLLING RESISTANCE:

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

ROTATION:

The changing of tires from front to rear or from side-to-side on a vehicle according to a set pattern; provides even treadwear.

RUN FLAT:

Damage sustained by a tire due to operation with insufficient air pressure.

SAFETY TIPS/TIRE MIXING:

For best performance, it is recommended that the same size and type of tire be used on all four wheel positions. In certain tires, casing ply material and ply construction may vary as indicated on the sidewall of the tire. Before mixing different types of tires in any configuration on any vehicle,be sure to check the vehicle manufacturer's owner's manual for its recommendations.

It is especially important to check the vehicle manufacturer's owner's manual when mixing, matching, or replacing tires on 4-wheel drive vehicles, as this may require special precautions. NOTE: Tires which meet the Rubber Manufacturers Association (RMA) definition of snow tires are marked M/S, M+S, or M&S. On such tires, this designation is molded into the sidewall. Tires without this notation are not recommended for snow driving. In severe winter conditions, the use of four (4) winter radial tires is recommended.

SEAT RIM:

Portion of rim on which beads rest.

SECTION HEIGHT:

The height of the tire sidewall, measured from rim to the outer tread.

SECTION WIDTH:

Linear distance between outside walls of an inflated tire without any load (exclusive of protruding side ribs and decorations).

SELF SUPPORTING SYSTEM (SSS):

A unique construction, that in an event of pressure loss, will allow the tire to operate with little or no air pressure for a limited time.

SELF-CLEANING:

Descriptive of a tire tread design to eject dirt and mud by natural flexing action of tire.

SERIES:

Tires with the same aspect ratio, or relationship of height to width inside the tire.

SHIMMY:

Wobbling of wheels from side-to-side on a vehicle. Shimmying can be caused by a variety of factors, including improperly balanced tires, poor alignment and bent wheels.

SHOCK ABSORBER:

A fluid type cylinder which stops the car from bouncing after the initial shock has been absorbed by the spring. Most cars have four shock absorbers.

SHOULDER:

The area of a tire where the tread and sidewall meet.

SIDEWALL:

That portion of a tire between the tread and the bead.

Sidewall abbreviations:

• BW--Black Wall
• BSW--Black Sidewall
• GSW--Gold Stripe wall
• ORBL--Outlined Raised Black Letter
• ORWL--Outlined Raised White Letter
• RBL--Raised Black Letter
• RWL--Raised White Letter
• RRBL--Recessed Raised Black Letter
• RRBL DIR--Recessed Raised Black Letter Directional
• WW--White Wall
• WSW --White Sidewall

SIPES:

Special slits within a tread block that increase wet and snow traction. Sipes provide more biting edges and allow for the dispersion of water from under the tread surface.

SIZE:

The combination of tire width, construction type, aspect ratio and rim size used in differentiating tires.

SKID:

To slip or slide on the road when tires lose their rolling grip.

SLIP ANGLE:

An angle formed by the direction of travel of a vehicle and the steered direction (that which the wheels are pointing). It is produced by distortions within the tire, due to external forces. Not to be confused by actual slipping or skidding.

SPEED RATING:

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

SPREADER:

Device for spreading beads of tire to examine or obtain access to inside.

SQUIRM:

The movement of a tires tread as it passes through the contraction cycle. Greatly reduced by belt systems and radial construction.

STABILITY:

Ability of tires to maintain direction of vehicle on curve without causing excessive body sway.

STATIC BALANCE:

State of balance in wheel when wheel is standing still.

STATIC LOADED RADIUS:

Distance from center of wheel to ground on vehicle which has rated load, normal inflation, and is not in motion.

STATIC WHEEL BALANCER:

Wheel balancer used to check wheel balance of tire not in motion. Also known as a bubble balancer.

STEEL BELTED RADIAL:

A radial tire made with steel belts as opposed to textile belts.

STREET HANDLING:

Indicates the tires ability to navigate the twists and turns of everyday driving conditions, as well as the ability to provide good "on-center" steering feel and true tracking for highway driving.

STUD:

A hard metal or plastic rivet which is inserted into a pinned tire for the purpose of improving winter traction.

TIRE:

A precisely engineered assembly of rubber, chemicals, fabric and metal designed to provide traction, cushion road shock and carry a load under varying conditions.

TIRE BALANCING:

Adding external weights to compensate for unequal distribution of tire weight. A small metal weight clamped to rim is used to correct an unbalanced tire.

TIRE CYCLES:

The basic attitudes through which a tire passes in the process of rotating on a car. There are three cycles, the normal cycle before road contact, the contraction cycle during road contact and the expansion cycle after road contact.

TIRE DESIGNATION:

An alphanumeric code molded into the sidewall of the tire that describes the tires size, including width, aspect ratio, rim diameter, load index and speed rating. Most designations use the P-Metric system.

TOE-IN:

Adjustment of front wheels so that they are closer together at the front than at the back. All wheels are set this way when new vehicle leaves the plant. Slight toe-in eliminates tendency of wheels to weave from side to side. All wheels should toe-in slightly. However, too much toe-in creates very heavy wear on the outer shoulder of the tire.

TOE-OUT:

Alignment of wheels so that they are closer together at back than at front. This condition creates excessive wear and should be corrected.

TRACTION:

The grip or friction, pull or bite between the tires and the road surface. Traction grades range from AA, A, B, C, with AA being the highest attainable grade.

TRAMPING:

A state in which a vehicle bounces up and down abnormally.

TREAD:

That portion of a tire that comes into contact with the road. It is distinguished by its tread design and rubber compound.

TREAD DEPTH:

The distance in thirty-seconds of an inch measured from the tread surface to the bottom of the grooves in a tire.

TREAD DESIGN:

The pattern of the tread.

TREAD ELEMENTS:

The parts of the tread design which are separated from each other and made distinct by the sipes and rib or lug design molded into the tire.

TREAD LIFE:

Length of service in miles before tread wears out.

TREAD RIB:

The tread section that runs around the circumference of the tire, separated by the tread grooves.

TREAD WEAR:

Expected durability of the tire tread.

TREAD SEPARATION:

Tread pulling away from body of tire.

TREAD WEAR INDICATOR:

Narrow bands, sometimes called "wear bars," that appear across the tread surface of the tire when only 2/32 inch of tread remains.

TREAD WIDTH:

The portion of the tread design that comes in contact with the road.

TRACTION:

The friction between the tires and the road surface; the amount of grip provided.

TUBE:

An airtight container placed inside tire casing to hold the compressed air.

TUNER:

Tuner dimensions are those with more of priority in aesthetics enhancement than true performance enhancement. Performance is still an important part of the equation, it's just second to aesthetics.

UNDER-INFLATION:

Insufficient air pressure in a tire for the amount of load carried.

UNDERSTEER:

The tendency of a vehicle to turn less sharply than the driver intends or the reluctance of a vehicle to leave the straight path ahead while steering. Example - A vehicle is said to have an understeer condition during a turn when the front tires have less grip on the driving service than the rear tires have and the vehicle tends to follow a straight line regardless of steering input. Understeer is also referred to by the term push.

UNDERTREAD:

Tread material between bottom of antiskid grooves and carcass.

UNIFORM TIRE QUALITY GRADING SYSTEM (UTQGS):