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Glossary of Tire and Wheel Terms

Whether you see it in your owner’s manual or hear it from one of our technicians when you come in for new tires, you may come across a tire or wheel term you aren’t familiar with. Action Gator Tire created this handy alphabetical glossary of tire and wheel terms to help you understand what your vehicle and its tires need to stay on the road and how to find the perfect tires and wheels for your vehicle.

A

Air Check

During an air check, you or a technician use a tire pressure gauge to find out how much air is inflating your tire. You should do an air check once a month, every time you get your tires rotated, or every other time you gas up, whichever is most frequent.

Air Pressure

Air pressure is the amount of air in your tire. Each vehicle has a recommended air pressure for optimal tire performance, and it will be listed in your owner’s manual. Air pressure is measured in PSI (pounds per square inch).

Airtight Synthetic Rubber

Modern “tubeless” tires use airtight synthetic rubber, which is made with virtually impermeable butyl rubber to replace the classic inner tube.

Alignment

Your vehicle’s suspension has many adjustable components. Alignment refers to the condition of these parts. Each vehicle has three alignment settings set to specification: camber, caster, and toe-in/toe-out. Worn suspension parts or severe impacts like hitting curbs or potholes can cause misalignment.

All-Season Tires

All-season tires provide reasonable traction in various road conditions such as dry, muddy, wet, icy, or snow-covered. However, they don’t provide exceptional traction under any circumstances, especially when compared to weather-specific tires like winter or summer tires.

All-Terrain Tires

All-terrain tires provide performance both on- and off-road. Often equipped on SUVs, trucks, and 4-wheel-drive vehicles that may go off-road, all-terrain tires have a more aggressive appearance and may cause more road noise than traditional truck tires.

Asymmetric Tread

Designed to provide a wide range of performance attributes in various conditions, tires with an asymmetric tread pattern have a continuously unique design across the tire’s width. The tread pattern closest to the inside of the tire focuses on winter and wet conditions, while the tread pattern on the outside of the tire tread provides better dry traction and improved handling. Asymmetrical tread patterns differ from symmetrical and directional tires.

Alphanumeric

Until the late 1970s, alphanumeric was a tire size designation that had numbers and letters such as F78-15.

Aspect Ratio

The proportion between a tire’s height and width is the aspect ratio. Appearing after the slash in the tire size code, the aspect ratio tells you the sidewall as a percentage of the width. As an example, a P205/65R16 tire has an aspect ratio of 65, meaning the sidewall is 65% of the width (205 mm).

B

Backspacing

Measured in inches, backspacing refers to the distance between a wheel’s mounting surface and innermost lip, which determines how your wheel will fit in your wheel well. Higher backspacing places the tire further under the fender, while lower backspacing puts the wheel toward or past the fender.

Balancing

For the smoothest ride, you need your tire and wheel assembly to rotate with evenly distributed weight. During a balancing service, a mechanic uses a wheel balancer to find imbalances that can cause vibrations while you drive. Then, the technician strategically puts weights on the wheel to compensate for any imbalances, providing a smoother ride.

Bead

At the very inside of a tire’s diameter lies the bead, a round hoop of steel wires which helps the tire stand and support weight.

Bead Chafer

A bead chafer acts as the contact point between the wheel and tire. It withstands the forces of driving, braking, and tire mounting.

Bead Filler

Bead filler transfers braking and propulsion torque from the wheel rim to the road surface contact area.

Bead Tension Structure

Providing lateral stability and flex to absorb road irregularities, bead tension structure involves two sidewall plies wrapped around each bead wire in opposite directions.

Belt

Commonly made of steel, the belt is a rubber-coated layer of cords between the tire’s tread and body plies. Belts may also be made from polyester, rayon, fiberglass, nylon, or other fabrics.

Bias Ply Tire

Mostly used on trailers, bias-ply pneumatic tires have plies at angles less than 90° to the tread centerline. Criss-cross plies offer extra strength but generate heat that limits the tire’s performance and wear. Radial tires have mostly replaced bias-ply tires.

Bolt Pattern

Referring to the diameter of an imaginary circle drawn through the middle of each bolt, a bolt pattern is the arrangement of bolt holes that keep the wheel fixed to the hub.

Breakaway

Breakaway describes a loss of traction when accelerating from a standing start or negotiating a curve, when tires slide against the road rather than gripping it.

Butyl Rubber

Virtually impenetrable to air and water, butyl rubber is the synthetic rubber used in modern tires.

C

Camber

One of the settings adjusted during an alignment service, camber is a measurement, in degrees, of the wheel’s inward tilt when viewed from the front of the vehicle.

Camber Thrust

Camber thrust is a lateral force developed due to the camber angle of the wheel, generated due to the deformation of the contact patch tread of the tire.

Carbon Black

Carbon black is a reinforcing filler that can be incorporated into the tire rubber compound to make the tire more resistant to wear.

Carcass Ply

Carcass ply cables, which are made from thin textile fiber cables bonded into the rubber, help determine a tire’s strength.

Carrying Capacity

Carrying capacity refers to how much weight a tire is meant to carry at a specific air pressure. A load inflation table will tell you how much air each tire size needs to support the vehicle axle weight.

Casing

Casing refers to the tire body beneath the tread and sidewalls. The carcass consists of rubber-coated fabric plies that contribute to shock absorption and carrying capacity.

Caster

Adjusted during an alignment, caster is the angle of an imaginary line drawn through a wheel’s steering axis and centerline.

Casting

Casting is part of the wheel manufacturing process where liquid metal is poured into a mold, which determines the wheel’s final shape.

Centerline

An imaginary line down the center of a vehicle or a wheel which helps to measure a vehicle’s alignment.

Centrifugal Force

Centrifugal force is the sensation of movement, such as when sitting in a turning car, even though no actual force is being applied to your body. Since there is no actual force, physicists refer to centrifugal force as a fictitious or pseudo force.

Cold Inflation Pressure

As you drive, heat builds up in your tires that can lead to an increased tire pressure reading. When possible, you should get a cold inflation pressure, which measures the air pressure in your tires as pounds per square inch before your tire experiences heat buildup from driving.

Compliance Cushion

Absorbing road irregularities for a smoother ride, a compliance cushion is an added rubber component between the tire belt and tread.

Contact Patch

The contact patch refers to the tread part of the tire that contacts pavement while driving.

Cord

Made from polyester, rayon, fiberglass, nylon, or steel, cord is strands of material forming the plies (tire layers).

Cornering Force

Cornering force is the force exerted on a tire when the car turns.

Crown Plies

Crown plies give a tire lateral and centrifugal rigidity, flex for a comfortable ride, and provide a rigid base for the tread for good fuel economy.

Curb Weight

Curb weight describes a vehicle with no passengers, normal equipment, and full fluid reserves.

D

Deflection

Deflection is the area where the sidewall and tread flex when the tread contacts the road.

Directional Tread Pattern

Used for water performance and evacuation, a directional tread pattern is usually v-shaped and can be mounted on either side of the vehicle as long as a tire professional installs it properly so the tire travels in the right direction. The tires have a sidewall designation on each side of the tire indicating the traveling direction of the tire on the vehicle.

DOT Identification

Tires that comply with Department of Transportation requirements for highway use have an alphanumeric code, called the DOT identification, which starts with the letters “DOT” and may have up to 12 additional letters and numbers with information like when and where the tire was made.

Drift

Drift happens when a vehicle strays from a straight path without the driver’s steering input.

Dry Traction

Dry traction describes a tire’s ability to grip the road while accelerating and braking.

Dry Zone

Providing improved handling on dry roads, the dry zone is large tread blocks along the outer edge of a tire.

Dual Tread Compound

A tire with two different compound types in the tread (usually an inside one for wet traction and an outside one for dry traction) has a dual tread compound.

Dually or Duals

Referring to two tires next to each other on an axle (meaning the axle has four, rather than two, tires), a dually increases load-carrying capacity and traction.

Dynamic Imbalance

The weight of a wheel and tire assembly should be equally distributed on either side of the centerline and around its circumference. A dynamic imbalance, when the weight is not equally distributed, can cause side-to-side shaking or a wobbling effect.

E

Eccentric Mounting

Eccentric mounting is when a wheel and tire assembly is mounted so the assembly’s center of rotation isn’t aligned with the hub’s center of rotation.

ECE Symbol

A European organization that develops motor vehicle requirements, ECE stands for “Economic Commission of Europe.” An ECE symbol means a tire meets European standards for branding requirements, physical dimensions, and high-speed endurance.

Extra Load (XL)

An extra load (XL) designation indicates a tire can carry a higher load than usual and has a maximum inflation pressure higher than the standard maximum.

F

Filament at Zero

Helping to enhance ride quality and steering precision as well as retaining tire shape, filament at zero refers to spiral-wrapped individual aramid/nylon or nylon reinforcing filaments placed either across the entire tread or just in specific portions atop the steel belts banded at zero degrees.

Fore-and-Aft Weight Transfer

Caused by acceleration, fore-and-aft weight transfer occurs when weight is transferred between the front and rear axles. On the other hand, braking causes weight transfer from rear to front.

Four-Wheel-Drift

Four-wheel-drift happens when a vehicle’s front and rear tires slide in a controlled manner. A driver can use the steering wheel and throttle to correct their course.

Forging

Forging is a wheel production process where pressure and heat reshape a block of alloy material into a wheel design.

Free Radius

Free radius is the radius of a wheel and tire assembly when not deflected under load.

Friction

Friction is the resistance of the tire tread as it moves against the road, which helps the vehicle grip the road.

G

Gross Axle Weight Rating

The Gross Axle Weight Rating (GAWR) refers to the maximum weight that can be distributed between the tires on each axle.

Gross Vehicle Weight

Gross vehicle weight is the total weight of a vehicle when loaded with cargo and passengers.

Gross Vehicle Weight Rating

Gross vehicle weight rating is the maximum weight a vehicle can support, including its own weight.

H

Handling

Handling refers to a tire’s responsiveness to steering input.

Heat Cycling

Heat cycling slowly heats a competition tire in a controlled environment before its first use to break it in. The heat buildup creates a longer tread life and more consistent traction.

High Flotation or Flotation Tires

With wider treads and lower sidewalls for improved traction on mud, soft soil, or sand in off-road situations, flotation tires are designed specifically for light trucks.

High-Performance Tires

Also sometimes called ultra-high-performance, high-performance tires have stiffer sidewalls and are rated for operation at higher speeds than other tires. They also grip, handle, and corner better than other tire types.

Highway Tires

Made for SUVs, crossovers, and trucks, highways tires are designed for wet and dry weather driving but not ice and snow.

Hub Cap

Typically made from affordable materials like aluminum or plastic, hub caps shield lug nuts from debris and may offer aesthetic appeal. Usually used on steel wheels, hub caps are typically easy to remove when necessary.

Hub-Centric

Hub-centric wheels are manufactured to perfectly fit the diameter of a vehicle’s hub. On the other hand, lug-centric tires match the vehicle’s lug pattern but have a larger mounting hole than the hub.

Hub-Centric Rings

Also called hub rings, hub-centric rings fill the gap between a vehicle’s hub and the hole in the mounting pad on an aftermarket wheel. While they aren’t required, hub rings can help limit vibrations at higher speeds.

Hydroplaning

A skimming effect when a tire loses contact with a road surface covered in water, hydroplaning refers to the loss of control driving in wet conditions can cause.

I

Imbalance

An imbalance is an uneven distribution of a wheel and tire assembly’s mass.

Indentation

Overlapping splices of fabric cords can create normal and safe indentations in the tire sidewall. Due to steel cable implementation, indentations don’t happen on treads.

Inflation

Inflation is the act of putting air in tires.

Innerliner

The innermost layer of rubber in a tubeless tire, the innerliner helps reduce air loss through the tire.

Interlocking Sipes

Interlocking sipes are S-shaped or zig-zag sipes that interlock for greater flexibility and extra grip.

K

Kilopascal

A kilopascal is a metric unit for pressure. 1 PSI equals 6.9 kPa.

L

Lateral Runout

A wheel wobbling side-to-side while it rotates causes vehicle vibration and is called lateral runout.

Lateral Weight Transfer

A lateral weight transfer is when a vehicle turns and centrifugal force transfers weight from the wheels on the inside of the curve to those on the outside.

Light Truck (LT)

Light truck is an auto industry term for pickups, smaller trucks, SUVs, and passenger vans.

Light Truck (LT) Tires

Light truck (LT) tires usually have higher load ratings and are typically required on heavy-duty vehicles due to their increased load-carrying capacity and ability to resist abuse caused by conditions that SUVs and trucks often encounter.

Load Carrying Capacity

Load carrying capacity says how much weight a tire can carry at its maximum inflation pressure.

Load Index

Corresponding to a tire’s load-carrying capacity, the load index is an assigned number from 0-279.

Load Range

Usually listed as letters associated with a specific ply rating, load range defines a range of maximum loads a tire can manage at a certain pressure.

Loaded Radius

Loaded radius is a measurement, in inches, from the ground to the wheel axle centerline when the tire is inflated properly for the given load.

Loaded Section Height

Loaded section height refers to the height of the part of the tire making contact with the road.

Lug-Centric

Lug-centric wheels match a vehicle’s lug pattern while having a bigger mounting hole than the hub. If necessary, you can use hub-centric rings to fill the gap and convert a lug-centric wheel to a hub-centric wheel.

M

Match Mounting

Match mounting matches a wheel’s low point with a tire’s harmonic high point, which ensures optimal ride performance.

Maximum Inflation Pressure

Molded on a tire’s sidewall, the maximum inflation pressure is a PSI limit to how much pressure a cold tire can be inflated to. You should generally follow the recommended PSI rather than the maximum inflation pressure.

Metric Tire Size System

Used by the European Tire and Rim Technical Organization (ETRTO), the metric tire size system describes tire size.

Misalignment

Misalignment happens when a vehicle’s suspension isn’t aligned properly, which can lower your tire’s life expectancy and cause improper tread wear patterns.

Mounting

Mounting is the act of installing a tire on a wheel while ensuring the tire bead is seated firmly on the wheel. New tires must be professionally mounted to wheels.

Mud and Snow (M + S, M / S, or M & S)

Exceeding a certain tread to void ratio, Mud and Snow rated tires have a tread designed to perform well in severe conditions.

N

Negative Camber

Used by racers for maximum cornering potential, negative camber is an alignment setting that leans the top of a tire toward a vehicle’s centerline.

Negative Offset

Moving the tire and assembly out past the fender, negative offset describes when a wheel mounting face is placed nearer the brake side of the wheel.

NHTSA

NHTSA stands for the National Highway Traffic Safety Administration.

Nominal Rim Diameter

Listed in the nearest whole number, nominal rim diameter is the diameter of a rim.

O

Off-Road Tires

Usually having large blocky tread patterns for better grip, off-road tires are designed for performing on non-paved surfaces such as sand, dirt, and mud.

Offset

Determining how a wheel fits in the wheel well, offset is the distance between the centerline of the wheel and its mounting surface.

Original Equipment (OE)

The tires a manufacturer puts on new vehicles are referred to as original e equipment (OE). They offer tires that provide the best ride and performance based on the vehicle’s characteristics.

Original Equipment Manufacturer (OEM)

Original equipment manufacturer refers to the maker of an original equipment part.

Overall Diameter

Overall diameter refers to the diameter of an inflated tire that isn’t carrying a load.

Overall Width

Typically measured in millimeters, overall width is the distance between a tire’s outer walls, including designs and lettering.

Overinflation

When you fill your tires above the recommended PSI rating, overinflation can cause an increased stopping distance, irregular wear, and a harsh ride.

Oversteer

Oversteering is when a vehicle turns sharper than the driver intends. Since the vehicle’s back end usually swings wide, an oversteering car is called “loose.”

Oxidation

Oxidation is a rusting process that happens when moisture contact’s a tire’s steel belt, typically due to damage. Oxidation can shorten a tire’s lifespan.

P

P-Metric

Meeting United States-based standardizing organization requirements using metric measurements, P-metric refers to a tire designation system American tire manufacturers introduced in 1977.

Passenger Tires

Focusing on proficiency in most driving conditions and value, passenger tires are made in sizes for coupes, sedans, and minivans.

Performance Tires

Focusing more on performance and high-speed usage, performance tires are usually used on high-performance passenger cars.

Penny Test

The penny test is a common way to check tire tread depth. Place an upside-down penny between a tire’s treads. If you can see the top of Lincoln’s head, you need new tires.

Permeation

Tires slowly leak air due to permeation, a natural process where vapor or liquid escapes from inside a solid.

Placard

Providing important vehicle information like seating capacity, gross vehicle weight, and cold tire inflation pressure, the placard is a small label normally located on the edge of the driver’s door or doorframe.

Plus-Sizing

Plus-sizing lets a driver customize the performance and look of their vehicle by changing the tire or wheel size.

Ply

Ply is a rubber-coated fabric layer that contains cords running parallel to each other. Layers of ply are located between the tread belts and innerliner and run from bead to bead.

Ply Rating

A ply rating is a letter which indicates the tire’s load carrying capacity in terms of its construction. “C” means the tire has a 6-ply load carrying capacity, although the tire has one or two plies of equivalent strength rather than six plies.

Pneumatic Tire

Pneumatic tires are designed to be filled with air.

Positive Camber

Causing tires to tilt away from a vehicle’s centerline, positive camber is an alignment angle where the tops of the tires are farther apart than the bottoms.

Positive Offset

Moving the wheel and tire assembly in toward the vehicle, a positive outset places a wheel’s mounting face closer to the street side of the wheel.

Proprietary Blended Compounding

Providing excellent performance in both dry and wet conditions, proprietary blended compounding is technology that creates a uniform compound blend.

PSI

The standard unit of measurement for air pressure in tires, PSI stands for pounds per square inch.

Pull

Resulting from improper wheel alignment, worn or improperly adjusted brakes, or irregular tire wear, pull is when a vehicle swerves to one side without the driver steering in that direction.

R

Radial Ply

In a radial ply tire construction, the cords in the body run perpendicular to the tread’s centerline.

R-Compounding

Designed for repeated heat cycles and maximum dry grip, R-compounding is a racing-derived compound optimized for performance on a track.

Revolutions Per Mile

Varying with load, speed, and inflation pressure, revolutions per mile (RPM) measures how many times a tire traveling one mile revolves.

Ribs

Ribs are the tread pattern around a tire’s circumference. Typically, you will find multiple ribs across a tire’s tread area.

Ride Height

Providing a reference point for alignment measurements, ride height is the distance between the vehicle frame and the road.

Ride Matching

To reduce vibration resulting from a tire and wheel assembly being out of round, ride matching matches the high spot of a tire with the low spot of a wheel to ensure the assembly is as close as possible to perfectly round.

Rim

The rim is the part of the wheel where the tire is mounted.

Rim Diameter

Rim diameter is the diameter of the rim bead seats that support the tire.

Rim Flange

A rim flange is the area of a wheel’s surface contacting the side of the tire bead to form an airtight seal.

Rim Width

Rim width is the distance between the two opposite inside edges of the rim flanges.

Rolling Resistance

Rolling resistance is the force necessary to keep a tire moving at a constant speed. A lower rolling resistance requires less energy to keep a tire moving.

Runout

Runout describes the way a wheel moves in and out, away from its true center, while it rotates. Excessive runout can cause the wheel to wobble.

S

Section Height

Measured in millimeters, the section height is the height of a tire from the rim to the outer tread.

Section Width

Measured in millimeters, the section width is the distance between the outside sidewalls, not including the design and lettering.

Series

The series is a numerical representation of a tire’s aspect ratio. For example, in a tire marked 225/ 60R-17, the “60 series” indicates that the tire’s section height is 60% of its section width.

Service Description

The service description is letters and numbers molded into a tire’s sidewall indicating the load index, load carrying capacity, and speed rating.

Shimmy

Usually caused by worn steering components, misalignment, or a dynamic imbalance, shimmy describes a side-to-side wobbling motion at the front of the vehicle, which you can feel through the steering wheel.

Shoulder

The shoulder is where a tire’s tread and sidewall meet. Some tire designs include shoulder blocks for improved traction.

Sidewall

The sidewall is the part of the tire between the bead and the tread. A lot of important tire information is written on the sidewall, like speed rating, tire size, load rating, UTQG rating, DOT identification, maximum PSI, and more.

Sipes

Sipes are special slits in a tread block which help increase traction, especially in snowy or wet conditions. Opening as the tire rolls onto the contact patch, then closing to break the surface tension on wet roads, sipes put more rubber in contact with the road by letting tread blocks flex and conform to the surface, which increases traction.

Size

Size is an alphanumeric expression which defines a tire in terms of height, width, aspect ratio, rim diameter, and construction type.

Slip

Slip is the difference between the rotational speed of a tire and the vehicle’s linear speed. As an example, a tire that is locked and sliding when a vehicle isn’t moving is operating at -100% slip.

Slip Angle

Slip angle is the difference between the direction a vehicle is traveling and the direction the wheel is traveling.

Speed Rating

Determined by lab testing, a speed rating is a letter system that identifies the maximum speed a tire can be driven for an extended time period.

Spoke

Spokes extend from the center hub to the outer edges of a wheel and connect to the rim. Wheels can have nearly any number of spokes, and aftermarket wheels may have unique finishes, colors, and designs.

Sprung Weight

The sprung weight is how much of a vehicle is supported by the springs, including the engine, frame, and body.

Stability

Stability is a tire’s ability to respond to external forces and steering inputs.

Staggered or Staggered Fitment

Staggered fitment is putting larger wheels and tires in the back of your vehicle and smaller ones in the front.

Standard Load

A standard load is how much weight a particular size tire can carry at a recommended air pressure.

Star Pattern

Preventing misalignment, ensuring uniform pressure, and helping keep the wheel centered, the star pattern is a pattern for tightening lug nuts when mounting a wheel and tire assembly to a vehicle.

Static Balance

Static balance exists when the weight mass is distributed evenly around a wheel’s axis of rotation.

Static Loaded Radius

The static loaded radius is the distance from the wheel’s axis of rotation to a supporting surface at a stated inflation pressure and given load.

Steel Belt

Ensuring uniformity during rotation and helping to prevent flats, a steel belt is a combination of rubber-coated steel cords that form a belt or strip under a tire’s tread.

Steering Response

Steering response refers to a vehicle’s reaction to a driver’s steering or the feedback drivers get through the steering wheel as they steer.

Steering System

Including the steering wheel, steering gear, linkages, wheel supports, and steering column, the steering system is the entire mechanism that lets a driver direct the vehicle.

Step Groove

Providing extra grip in deep snow, a step groove is a design feature at the groove base of a tire tread.

Structure

Structure refers to a tire casing’s construction. Identified by the letter “R,” most of today’s tires are radial structure tires.

Studs or Studding

Providing extra traction in soft ice and hard-packed snow conditions, studdable winter tire treads have metal inserts (studs) that accept a specific pin. Since they damage roads, some places prohibit studded tires or limit them to the snowiest winter months.

Studded Tires

Studded tires are winter tires that have metal studs for better traction in deep snow.

Suspension

The suspension includes all the shock absorbers, springs, and linkages needed to suspend a vehicle’s body, engine, frame, and drivetrain above the wheels.

Symmetrical Tread

Providing improved performance on specific roads in certain conditions, symmetrical tread has a uniform pattern on both sides of the tread.

Synthetic Rubber

Synthetic rubber is man-made. Today, tires are mostly made of synthetic rubber rather than natural rubber.

T

T&RA

T&RA stands for Tire and Rim Association.

Teardrop Siping

Easing the shear force at high-stress points which can crack the sipe and allowing the tread block to flex easier, teardrop siping is small teardrop shapes in the ends of each sipe.

Tensile Strength

Tensile strength is an object’s resistance to breaking or stretching when it’s placed in tension. Steel belts are compared by tensile strength.

Tire Construction

Tire construction describes how a tire’s plies are assembled. “B” means bias construction, with plies running diagonally across the tire, while “R” represents radial construction, with plies running radially across the tire.

Tire Designation

Describing aspects of a tire’s size, such as aspect ratio, width, load index, rim diameter, and speed rating, the tire designation is an alphanumeric code molded onto a tire’s sidewall. Most designations use the P-metric system.

Tire Mixing

Potentially leading to variations in a vehicle’s handling characteristics and ride, tire mixing involves using more than one type, brand, or size of tire on one vehicle.

Tire Pressure Gauge

A tire pressure gauge is a tool used to measure a tire’s air pressure.

Tire Pressure Monitoring System (TPMS)

Creating an alert on a vehicle’s dash when a tire’s air pressure drops below a certain level, the tire pressure monitoring system (TPMS) is an automated system that monitors the air pressure in a vehicle’s tires.

Tire Rotation

Tire rotation is a maintenance service which helps ensure tires wear evenly by moving your tires from side to side or front to back in a prescribed pattern.

Toe

Adjusted during alignment, toe describes the symmetry between two parallel tires when viewed from above. Toe-out means the front of the tires point out toward the road, while toe-in means the front of the tires veer in toward the engine.

Toe-Out Turns

Occurring when the two front wheels steer at different angles when turning, toe-out turns describe how a vehicle’s wheels on the inside of a turn follow a smaller radius than those on the outside.

Torque

Typically measured in Newton-meters or foot-pounds, torque refers to twisting or turning effort.

Torque-Locking Sipes

For added rigidity during cornering, torque-locking sipes have vertical undulation.

Torsion Bar

Acting like a coiled spring which absorbs energy by turning, a torsion bar is a long, straight bar attached to the vehicle frame from one end of a suspension part to the other.

Touring Tires

A middle ground between performance and passenger tires, touring tires offer a balance of performance attributes and ride quality.

Track

Track is the distance between the outer tread edges of two tires on the same axle.

Traction

Traction describes the level of grip a tire has on the road and the friction between the road surface and the tire.

Tramping

Tramping is a condition where a car bounces up and down abnormally.

Tread

Made from a wearable, durable rubber layered on top of the tire carcass, the tread is the outermost part of the tire which contacts the road.

Tread Act

Making tire pressure monitoring systems mandatory for all vehicles built after 2007, the Tread Act is a federal law that increased vehicle safety regulations.

Tread Buffing

Also known as shaving, tread buffing involves scraping rubber off the tread.

Tread Depth

Tread depth is a measurement of how much usable tread is left on a tire. You can find the tread depth by measuring from the groove base to the tread top in the outside, inside, and centerline of the tread. The final tread depth is the lowest of the three measurements.

Tread Grooves

Tread grooves are the spaces between the tread blocks in lateral or circumferential directions.

Tread Life

Tread life is the life of a tire before it is replaced.

Tread Pattern

Tread pattern refers to the tire tread’s rubber design, which incorporates blocks, sipes, and grooves. The arrangement and shape of the tread pattern elements provide certain performance aspects and qualities.

Tread Rib

The tread rib is the tread section that goes around the circumference of the tire separated by tread grooves.

Treadwear Indicator

Also called wear bars, the treadwear indicator involves narrow bands across the tread that indicate when 2/32” of tread remains.

Tread Width

Tread width is the width of a tire’s tread.

TRI Side-by-Side Compounding

TRI side-by-side compounding makes it possible to perfectly place three different rubber compounds across a tire’s tread.

U

Ultra-Low Profile Technology

Enhancing the mountability and durability of tires with extremely short sidewalls, ultra-low profile technology involves a specialized bead compound, bead area, and sidewall shape.

Ultra-High Performance Tires

Also called UHP, ultra-high performance tires are engineered for the most capable and sophisticated sports cars. They provide maximum performance, including high-speed stability and optimal cornering response.

Underinflation

Causing reduced fuel economy and premature tire wear, underinflation happens when tires aren’t filled with enough air, which can happen naturally over time.

Understeer

Understeer is a handling characteristic where the front tires break loose since they are running a larger slip angle than the back tires.

Undertread

Acting as a comfort-enhancing cushion, undertread is a material between the top layer of steel belts and the bottom of the tread rubber.

Uni-Directional Tread

Also called directional tread, uni-directional tread refers to a tire intended to rotate in only one direction.

Unsprung Weight

Unsprung weight is the weight of a vehicle’s components that aren’t supported by its springs. This includes the rear axle assembly, outboard brake assemblies, tires and wheels, springs, shock absorbers, anti-roll bars, and suspension members.

UTQG (Uniform Tire Quality Grading)

UTQG (Uniform Tire Quality Grading) is a tire information system that gives consumers ratings that describe a tire’s treadwear rating, temperature (A to C), and traction (AA to C). Shown on the tire sidewall, tire manufacturers use standardized test procedures to determine these ratings, which can only be used to compare tires made by the same manufacturer, not between different manufacturers.

V

Valve

A valve is a device mounted in the wheel that restricts or allows airflow out of a tire. Valves include caps that prevent unwanted air escape, keep out moisture, and maintain cleanliness.

Variable Angle Sipes

Enhancing lateral grip, variable angle sipes are tread blocks with the siping set at three different angles.

Variable Contact Patch

Using a combination of underlying belts and asymmetrical tread patterns, a variable contact patch is a system that maximizes the contact patch area while cornering.

Variable Integrated Pitch

To minimize noise, variable integrated pitch is a process where tread blocks of different sizes are placed around a tire’s circumference.

Variable Thickness or Bidirectional Sipe

Variable thickness and bidirectional sipe are two types of sipe technology which increase a tread’s rigidity under loaded conditions like braking, cornering, or accelerating. This technology lets tread block surfaces lock together in both longitudinal and latitudinal directions, which results in short braking distances, responsive steering, and better transmission of engine torque to the driving surface.

Vertical Bouncing

Vertical bouncing happens when a vehicle’s weight is not evenly distributed around a wheel’s axis of rotation, which you can feel through the steering column, seat, and floor.

Viscous Planing

Viscous planing is a road condition where rain wets a road that was dry and allows oil on the road to rise up, causing the road to be extremely slippery, even with thin levels of moisture. As rain continues, it lessens the condition be washing away the oil.

Vulcanization

Improving its resilience and strength, vulcanization is an irreversible process of heating rubber under pressure.

W

Wander

Caused by worn tires, steering abnormalities, crosswinds, pavement irregularities, or suspension misalignment, wandering is a vehicle’s tendency to stray from its intended direction of travel.

Wet Traction

Wet traction describes a tire’s ability to provide vehicle control and grip on wet roads in addition to resistance to hydroplaning.

Wheelbase

The wheelbase is the distance from the rear wheel center to the front wheel center on the same side of the vehicle.

Wheel Weights

Wheel weights are small weights attached to a wheel during balancing. They may either clip onto the lip of the wheel or have an adhesive strip to be applied to the wheel barrel.

Winter Tires

Winter tires are also called snow tires, and they have a special compound and tread that offers improved traction in snow. They have a designation of M+S, M&S, or M/S on the sidewall and have a three-peak mountain snowflake symbol.

Z

Zero Offset

Zero offset is when the mounting face of a wheel aligns directly with the wheel’s centerline.

Zero Toe

Zero toe is when tires on the same axle are parallel, so the fronts and backs of the tires are equidistant.

Get New Tires in Florida

If you need new tires, tire repair, or any auto service, stop by your nearest Action Gator Tire location today. We have 25 locations across Central Florida to serve you. Find your nearest location and make an appointment now.

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