30-DAY GOODYEAR PLEDGE: A Goodyear pledge that allows consumers to drive on their new tires for 30 days before deciding on whether they want to keep them or exchange them.
2D BLADES IN THE CENTER ZONE: These blades offer enhanced stopping and starting power on snow and ice.
3D BUBBLE BLADE™ INTERLOCKING SYSTEM: An interlocking system that helps enhance dry weather handling.
3D TREDLOCK® TECHNOLOGY: Blades in the shoulder zone that offer enhanced wet and winter traction and that lock together for confident grip in turns.
ACTIVEBRAKING TECHNOLOGY: Offers enhanced stopping power on wet and dry roads. Activebraking technology can be found on tires such as the Eagle® F1 Asymmetric 2™.
ADAPTIVE SIPEGRIP TECHNOLOGY: 2 different types of sipes that align for both extra grip in winter conditions as well as improved dry and wet handling.
AIR PRESSURE (AKA INFLATION PRESSURE): The force exerted by air within a tire, expressed in pounds per square inch (PSI), kilopascals (kPa) or bars.
ALIGNMENT: Adjustment of steering and suspension components as specified by the vehicle manufacturer to facilitate the most efficient operation of all tire/wheel assemblies as related to vehicle control and tire wear.
ALL-SEASON TIRES (AKA ALL-SEASON TIRES): Tires that are for performance in a variety of road conditions in all seasons of the year. An all-season tire must meet specified RMA (Rubber Manufacturer's Association) criteria and will carry a "M+S", "M&S", or "M/S" designation on the sidewall.
ALL-TERRAIN TIRES: Tires designed with more open space between tread lugs to offer more traction on difficult or rugged terrain.
APPROVED RIM WIDTHS: The range of rim widths (distance between the two inside edges of the rim flanges) on which a tire should be mounted.
ARAMID: A synthetic fiber used as a reinforcement material in some tires. DuPont™ Kevlar® is an example of an aramid fiber.
ASPECT RATIO: Numerical term that expresses the ratio between section height of the tire and the cross-section width. Aspect ratio of 70 means that the tire section is approximately 70% as high as it is wide.
ASYMMETRICAL: A tire design in which the tread pattern or internal construction on one side of the tire centerline differs from the other side.
BEAD: The section of the tire that rests on and holds the tire to the rim. Bead also refers to the round hoop of high tensile steel wires, which forms the core of that portion of the tire. For information on proper tire installation, see our tire installation services page.
BELT: A rubber coated steel or fabric layer that runs circumferentially around a tire between the tread and the plies and is usually oriented at opposite angle to another belt.
BIAS PLY: A tire with cords running at an acute angle to the circumferential centerline of the tire.
CAMBER: A vehicle suspension setting indicating the degree of a wheel's inward or outward tilt from vertical. This angle is adjusted in order to keep the outside tires flat on the ground while under load and turning.
CARBON BLACK: A material that acts as reinforcing filler in tire rubber compounds.
CARCASS AND CASING: Terms for the tire body beneath the tread and sidewalls. Casing usually means with the belts (retread industry). Carcass may refer to down to the plies without belts.
CENTERLINE: The imaginary line drawn circumferentially around a tire on the tread surface at the center of the tread.
COMFORT LAYER: An exclusive comfort layer in the tread designed to provide, on average, 20% more cushion than standard passenger tires (based on internal testing)**. The Assurance® ComforTred® tires feature a comfort layer that helps provide a smooth, quiet ride.
**Comparison of industry data for T, H & V speed-rated tires versus Goodyear Assurance ComforTred Touring. Standard Goodyear Internal Ride test – P215/60R16, 2008 Toyota Camry LE V6 railroad track at 35 mph vs. Michelin Primacy MXv4.
COMFORTEDGE® SIDEWALLS: Sidewalls that help provide a versatile balance of both comfort and handling.
CONSTRUCTION: How the plies of the tire are assembled. "R" stands for radial, which means the plies run radially across the tire. "B" stands for bias construction, which means that the plies run diagonally across the tire.
CONTACT PATCH (AKA FOOTPRINT): The total area of the tread that is in contact with the road during operation.
CORD: Twisted fibers or filaments in the plies or belts to help provide tire strength. Cords are often made from aramid, fiberglass, rayon, polyester nylon, or steel.
CROSSOVER AND SPORT UTILITY VEHICLES (CUV/SUV): A vehicle built on a car or truck platform, combined with sport utility features.
DEFLECTION: The difference between the unloaded and loaded section heights of a tire at a given load and inflation pressure.
DIRECTIONAL TREAD: A tire tread pattern (usually arrow or "v" shaped) that is designed to offer improved performance when rotating in one direction. Normally used in high performance and winter tire design.
DOT NUMBER: The D.O.T. number is a code that one can find on the sidewall of all over-the-highway tires signifying the fact that the tire complies with the U.S. Department of Transportation motor vehicle safety standards. The code identifies the manufacturer, manufacturing plant, tire size, tire type and the week and year of manufacture.
DRY ZONE: Large tread blocks along the outer edges to help provide confident handling on dry roads.
DUAL AQUACHANNEL® GROOVES: Grooves that help evacuate water from the tread face to provide great wet traction.
DUPONT™ KEVLAR® LAYER: An extra layer made with DuPont™ Kevlar® for toughness.
DUPONT™ KEVLAR® REINFORCED SIDEWALLS: DuPont™ Kevlar® reinforced sidewalls help increase sidewall puncture resistance by 35%***
***Source: Goodyear Sidewall Penetration Energy – LT285/70R17 LR-D-65 psi.
DURAWALL™ TECHNOLOGY: An exclusive technology that helps resistance to cuts and punctures in the sidewalls.
DUROMETER: An instrument used to measure the hardness of rubber. The value measured is expressed in terms referencing the type of scale used, for example "50 Shore A hardness".
EAGLE® TIRES: Families of tires typically applied to more sporty type vehicles with enhanced steering precision, confident handling and speed rating. Eagle® tires are designed with reinforced sidewalls for enhanced maneuverability.
EVOLVING TRACTION™ GROOVES: Traction grooves that help maintain confident traction in rain and snow as the tire wears. Learn more about how the AssuranceCS TripleTred tires provide confident traction.
FORTERA® TIRES: Families of tires developed for crossover vehicles, SUVs and light duty pickup trucks that provide a smooth and quiet ride and all season performance in a variety of wet and dry road conditions. Fortera® tires also offer stable handling.
FUEL EFFICIENT TIRES: Tires with low rolling resistance which can help improve fuel efficiency.
GROOVES (AKA TREAD GROOVES): Grooves are the spaces between two adjacent tread ribs or lugs. Some tread grooves help evacuate water from the road underneath the tire.
GROSS VEHICLE WEIGHT: The maximum allowable weight of a vehicle including the full load of occupants, cargo and fuel.
HANDLING (AKA PERFORMANCE HANDLING, STREET HANDLING): Handling describes the responsiveness of the tire to steering inputs.
HIGH FLOTATION TIRES: These light truck tires are for supporting a load on soft, yielding terrain. Size nomenclature will include the outside diameter, section width, construction type, rim diameter and "LT" as a suffix and might look like "31X10.50R15LT".
LIGHT TRUCK TIRES: Tires designed for non-commercial light trucks, pickups, passenger vans or SUVs. If you are looking for light truck tires, our Wrangler tire family might be right for you.
LOAD INDEX: A numerical code associated with the maximum load a tire can carry at the speed indicated by its speed symbol (rating) under specified service conditions up to 210 km/h. Special reduced loads apply for speeds above 210 km/h.
LOAD RANGE: An alphabetic code that designates for a specific tire size the maximum load a tire can carry at a defined inflation pressure.
LOW PROFILE TIRE: A tire in which the cross section has a squat appearance (section width is wider than the section height), such as in high performance tires.
LT METRICS: A tire with a "LT" prefix in the size designation and identifies that it is primarily intended for service on light trucks.
MAX INFLATION PRESSURE: The maximum amount of pressure that a cold tire can be inflated to; this number can be found molded onto the tire's sidewall. If you're looking for more information on proper tire inflation, take a look at our tire pressure service page.
MAX TIRE LOAD: The maximum weight for which a tire is built to support at the rated inflation pressure. To learn more about a tire's load capacity, visit our load index page.
MICROGROOVES (AKA SIPES): Grooves within the tire tread that run circumferentially, laterally, or diagonally. They increase driving stability, pulling and braking ability, and improve the evacuation of water from the road surface. For information on the different types of microgrooves featured on Goodyear tires, explore our technology glossary.
MISALIGNMENT: A condition with one or more parts of the steering mechanism outside of their specified service range causing unsatisfactory operation of the tires/wheels and vehicle. Misalignment can result in fast or uneven tread wear. For professional services, find a Tire & Service Network location near you.
MOUNTING: Installing the tire onto the wheel. It is important to have new tires professionally mounted. For professional services, find a Tire & Service Network location near you.
ORIGINAL EQUIPMENT FITMENT: Original Equipment (O.E.) tires are tires that came equipped on a new vehicle at the time of purchase. These tires are selected by the vehicle manufacturer in order to help provide optimal performance based on the characteristics of the vehicle.
OVERALL DIAMETER: An inflated tire's overall diameter (without any load) is twice the tire section height plus the nominal rim diameter.
P-METRIC: A tire with a "P" preceding the size designation and identifies that it is primarily intended for service on passenger cars.
PERFORMANCE TIRES (AKA MAXIMUM PERFORMANCE, HIGH PERFORMANCE, ULTRA-HIGH PERFORMANCE): Performance tires offer superior handling, grip and cornering ability compared to standard tires. They're rated for operation at higher speeds.
PSI: Pounds per square inch - a measurement of tire inflation pressure.
PLY: A layer of rubber-coated parallel cords that form a component of the tire casing. Sometimes the belts (or breakers) are referred to as plies.
RIM: The portion of the wheel to which a tire is mounted.
RIM DIAMETER: The diameter in inches of the wheel measured at the bottom of the flange. Always replace a tire on a rim with another tire of exactly the same rim diameter designation.
ROLLING RADIUS: The distance from the center of the wheel (axle) to the road under any given condition of load and inflation.
ROLLING RESISTANCE: The force necessary to keep a tire moving at a constant speed. The lower the rolling resistance, the less energy needed to keep a tire moving - which means more savings on fuel. For more information, take a look at our Assurance® Fuel Max® tire detail page.
ROTATION: The moving of tires from corner to corner on a vehicle according to a set pattern; this helps to provide even tread wear.
RUN ON FLAT TIRES: Run On Flat tires are designed to help enable a vehicle to drive with a deflated tire under specified conditions such as driving at a top speed of 50 mph for up to 50 miles.
SECTION WIDTH: The cross sectional distance between outside sidewalls of inflated tires (without any load), not including any lettering or design.
SHIMMY: A rapid sideways vibration of the front wheels usually caused by worn or damaged steering components or unbalanced tires. If you're experiencing this problem, we recommend finding a Tire & Service Network location near you.
SIDEWALL: The part of the tire in between the tread and the bead. Certain tires offer reinforced sidewalls in order to increase resistance to cuts and punctures.
SIPES: A narrow slit within a tread block. These slits are designed to provide biting edges for traction.
SIZE (TIRE SIZE): An expression used to differentiate tires by defining the particular tire dimensions in terms of width, rim diameter, aspect ratio and construction type.
SPEED RATING: An indexed alphabetical code that refers to the maximum speed that a tire is rated by the tire manufacturer.
CROSSOVER AND SPORT UTILITY VEHICLES (CUV/SUV): A vehicle built on a car or truck platform, combined with sport utility features.
STABILlITY: The ability of a tire to respond to steering inputs and to external forces.
STUDDED TIRES (AKA TIRE STUDS): Hard metal or plastic rivet-like devices that are inserted into a pinned tire. Tire studs are designed to improve ice traction. Check state, provincial or local regulations to determine if studded tires are permitted for use.
SQUIRM: The rubbing motion of the tread against the road surface as the loaded tire rotates.
SUMMER TIRES: Summer tires are developed exclusively to help provide an unsurpassed blend of traction and handling in warmer temperatures. They are designed with technologically advanced materials to perform on wet and dry roads, but are not recommended for ambient temperatures below 40°F/4.4°C.
TIRE BALANCING: When there is an unequal distribution of tire weight, the act of adding external weights in order to achieve equal weight distribution and improved ride is known as tire balancing.
TIRE CHAIN: A flexible, metal chain that attaches to the tire for enhanced traction on snow or ice.
TIRE PRESSURE GAUGE: A tool used to measure a tire's air pressure properly.
TIRE PRESSURE MONITORING SYSTEM: An automated system that monitors the air pressure in a vehicle's tires in order to alert the driver when the pressure drops below a pre-determined level.
TIRE REVS PER MILE: Number of tire revolutions per one mile at rated load and inflation; also called rpm.
TIRE SECTION WIDTH: The width of the tire from sidewall to sidewall.
TIRE SIZE CALCULATOR: A calculator tool that compares the measurements of two tires' diameter, width, sidewall, circumference, and revolutions per mile.
TIRE SIZE NOMENCLATURE: The system designating the tire size along with other information on the particular tire, which may include intended service type, nominal section width, nominal aspect ratio, construction, rim diameter and load capacity. There are various forms of size nomenclature such as P-metric, LT-metric, hard metric, alphanumeric and LT flotation. This code can be found on the sidewall of each tire and might look something like "245/65R17".
TIRE TYPE MARKING IN THE TIRE SIZE: A "P" designation means that it is a passenger car tire. An "LT" designation means that it is a light truck tire.
TRACTION: The grip or friction between the tires and the road surface.
TREAD: The part of the tire that comes into contact with the road surface.
TREAD DEPTH: The distance measured from the tread surface to the bottom of the grooves in a tire.
TREADWEAR INDICATORS: Raised bars of rubber molded at a height of 2/32 across the bottom of the tread grooves on a tire. When the tread wears down to these bars, the tires should be replaced.
TREAD WEAR: The loss of tread depth as a tire is in service. Proper maintenance of your vehicle and tires, including maintaining proper inflation pressure, will result in even tread wear and will extend the useable tread life of the tires.
UNDERSTEER: A handling characteristic where the front tires have a larger slip angle than the rear tires, making the vehicle tend to turn less sharply than the wheels are pointed.
UNIFORM TIRE QUALITY GRADE: A series of ratings prescribed by the government and determined by the tire manufacturer, which rates a tire's treadwear (a number representing treadwear as a percentage of a standard reference tire), traction (from AA to C) and temperature (from A to C).
WINTER TIRES (AKA SNOW TIRES): A winter tire is a tire with a tread design and compound made specifically for snowy and icy conditions. Identified by M&S, M+S or M/S markings on the sidewalls. Tires designed for use in severe snow conditions are further identified with a pictograph of a mountain with a snowflake on the sidewalls and must meet specific snow performance test requirements.