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Saturday, June 24 2017 @ 08:19 AM EDT

Car Talk Terms

Grab Bag - Misc.
  • What does Bump Steer mean? 
  • Is cornering force important? 
  • Is my Lateral Runout causing me issues?

 

Accelerator A chemical which speeds the vulcanization of rubber; used in tire compounds to reduce curing time.
Activator A rubber compound chemical used to help initiate the vulcanization process.
Adjustment A prescribed allowance given to a customer toward the replacement of product pursuant to the warranty.
Aging A reduction of physical and chemical properties of rubber by oxidation over a period of time.
Air Pressure Force exerted by air within a tire, expressed in pounds per square inch or kilopascals.
Alignment

Angles of the tire and suspension axes relative to each other and the ground: caster, camber, toe.

Also, the adjustment of components to bring them into a predetermined position for the most efficient

operation of wheel and vehicle for proper even tire wear.

Alpha-Numeric

A load-based tire sizing system containing the load capacity, type of tire construction, aspect ratio,

and the rim diameter in inches.

Anti-Roll bar

A steel torsion bar, linking the left and right side of a suspension. It comes into play during cornering.

As the car leans in a turn, the anti-roll bar resists this leaning by transferring more weight to the outside tire.

It provides a means to achieve good handling from stiff roll resistance while maintaining a comfortable

ride through soft springs.

 

Click "read more" below to learn about these terms and more


 

Term Definition
Accelerator A chemical which speeds the vulcanization of rubber; used in tire compounds to reduce curing time.
Activator A rubber compound chemical used to help initiate the vulcanization process.
Adjustment A prescribed allowance given to a customer toward the replacement of product pursuant to the warranty.
Aging A reduction of physical and chemical properties of rubber by oxidation over a period of time.
Air Pressure Force exerted by air within a tire, expressed in pounds per square inch or kilopascals.
Alignment Angles of the tire and suspension axes relative to each other and the ground: caster, camber, toe. Also, the adjustment of components to bring them into a predetermined position for the most efficient operation of wheel and vehicle for proper even tire wear.
Alpha-Numeric A load-based tire sizing system containing the load capacity, type of tire construction, aspect ratio, and the rim diameter in inches.
Anti-Roll bar A steel torsion bar, linking the left and right side of a suspension. It comes into play during cornering. As the car leans in a turn, the anti-roll bar resists this leaning by transferring more weight to the outside tire. It provides a means to achieve good handling from stiff roll resistance while maintaining a comfortable ride through soft springs.
Antioxidant A chemical, which when added to a rubber compound, prevents surface oxidation; used in tire tread and sidewall compounds to prevent weather checking and cracking.
Aspect Ratio The dimensional relationship between tire section height and section width; section height divided by section width.
Axial Play The up-and-down movement of a ball joint.
Axle A cross support of a vehicle on which its road wheels turn.
Backspacing The measurement from the back of the bolt pad to the back edge of the rim; used to calculate offset and determine where the back of the bolt pad is located in relation to the rim width, sometimes referred to as rearspacing.
Balance A uniform mass distribution of a tire and wheel assembly about its axis of rotation.
Bale Rubber The form in which solid rubber is shipped to tire manufacturers.
Ball Joint A ball-and-socket connection that lets a steering knuckle move in several directions at the same time.
Banbury Mixer An enclosed mixture machine for the production of rubber materials.
Bead The area of the mounted tire which seats against the wheel.
Bead Filler A rubber extrusion in the bead area of a tire; used to permit a smooth contour of casing plies around the bead and to the lower sidewall. Also used in enlarged form to stiffen the lower sidewall of a tire.
Bead Seat The position where the tire rests and seals on the inside of the rim.
Belt An assembly of fabrics and/or wire used to reinforce a tire's tread area. In radial tires, it also constrains the outside diameter against inflation pressure and centrifugal force.
Belt Edge Wedge or Insert An extrusion of rubber placed under the edges of a belt; used in radial tires to improve durability.
Belted Bias Tire A bias tire with additional reinforcing belt(s) between the casing plies and the tread.
Bias Tire A tire built with two or more casing plies which cross each other in the crown at an angle of 30 or 45 degrees to the tread centerline.
Bladder A rubber bag used inside a tire during the molding and curing process; contains hot water steam which presses the inside of the tire into the mold.
Blemish Tire A tire with a cosmetic or minor uniformity imperfection but whose safety and performance are unaffected.
Block Part of a tire tread pattern created by lateral (side-to-side) grooves.
Body Tire structure except for tread and sidewall rubber.
Bolt Circle Often referred to as the bolt pattern; the diameter of an imaginary circle drawn through the center of each lug hole.
Braking Torque Torque applied by a brake to a tire/wheel assembly which slows or stops the vehicle.
Breakaway The point at which tire cornering traction is lost.
Bump Steer A steering effect resulting from toe or camber changes as the suspension moves up and down.
Calendar A machine consisting of two or more rolls that continuously sheets a thin ply of rubber compound or coats a fabric with a rubber compound.
Camber The angle that the tire is leaning measured from true vertical. The inward or outward tilt of the wheel/tire at the top.
Camber Thrust The cornering force developed by a tire due to its camber. a force in the same direction as the leaning of the tire.
Carbon Black Very fine, specially structured particles of carbon; used in rubber compounds as a reinforcing filler.
Carrying Capacity Amount of load that a tire can carry at a given inflation pressure as established by the Tire and Rim Association.
Casing (Carcass) The structure of tire cords locked around wire beads, (most often used in relation to worn tires).
Caster The angle between the tire vertical and the steering pivot axis; the backward or forward tilt of the steering knuckle pivot points.
Center of Gravity The center balance point of a vehicle; the single point where a car would be supported without tipping up or down.
Centerline A plane dividing a tire, wheel, or vehicle into two symmetrical halves.
Centrifugal Force The force that tends to throw a tire away from the center of rotation same as LATERAL FORCE.
Chafer Abrasion resistant rubber coated material to help prevent the tire's beads from rim damage and chafing.
Change-Over Removal of tires placed on car or truck by the manufacturer prior to significant use, and substitution of better or more suitable tires.
Chapman Strut A rear suspension system which operates on the same principle as the MacPherson Strut; it uses lower links or a control arm and a long spring-shock strut.
Chassis The frame, suspension system, engine, and drive train of a vehicle; the assembled parts of an automobile without the body.
Coefficient of Friction The force required to slide an object, divided by the weight of the object; this indicated the difficulty in sliding one surface against another.
Coil Springs Suspension components of coiled spring steel that compress and respond to road pressure, permitting the up-and-down movement of a vehicle as it goes over road bumps and dips.
Cold Inflation The pressure in a tire that has been driven less than 1 mile or has been standing for three hours or more.
Compliance Steer A steering effect caused by the deflection or compliance of bushings, joints, and other suspension components under loads and forces.
Compounding Refers to the mixture of ingredients that go into the rubber used in a tire. Different chemicals or types of compounds affect wear, traction, cut resistance or other properties of a tire.
Concave Molding A process by which the center tread area of a tire is depressed in the molding stage. When inflated, the tread flattens out against the road surface more perfectly than a convex molded tire.
Control Arm A device used to connect the unsprung position of a suspension to the sprung chassis, which allows suspension travel.
Cord Fabric or steel wire strands forming plies and belts in tires.
Cord Angle The degree at which the plies or belts cross the center line of any given tire.
Cornering Force The force that turns a car around a corner. The opposite of lateral or centrifugal force.
Cross Pattern The sequential torquing of the lug nuts in a pattern across from one another.
Cross Section Width External sidewall to sidewall measurement of inflated tire, exclusive of ornamental ribs and lettering. Sometimes called section width.
Crown The region between the shoulders of the tire.
Crowned Road A road design with a slope or pitch from its center to the curb or shoulder in order to facilitate water drainage.
Curb Guard A rubber protrusion running circumferentially around some tires just above the whitewall to prevent curb scuffing on the whitewall area of a tire.
Curb Weight The total weight of a vehicle with no passengers and a full tank of gas.
Cure To vulcanize; also time and temperature conditions used to vulcanize a tire.
Custom Wheel An aftermarket wheel designed to improve performance and enhance appearance and comprised of one, two, or three pieces.
Design Rim A rim with a specified width; used to measure tire dimensions.
Directional Stability The ability of a car to travel in a straight line with a minimum of driver control.
Dog Tracking A condition where the rear wheels do not follow the path of the front wheels.
DOT A tire branding symbol which denotes the tire meets requirements of the Department of Transportation.
Double A-Arm A suspension system which uses two "A"-shaped links or arms of unequal length to attach the upright supporting the wheels to the frame.
Drive Wheel Application Describes tires which are designed specifically for optimum performance on drive wheels.
Dual Compound Tread A tire tread with two rubber compounds.
Duals Two tire and wheel assemblies, mounted on one side of an axle.
Durometer A measure of the hardness of a rubber compound; its resistance to penetration of a spring-loaded blunt needle.
Dynamic Balance Balance in motion. The balance of a wheel while it is rotating. a condition in which a tire and wheel assemble has weight distributed equally on both sides of the wheel's axis of rotation.
E.C.E. Symbol A tire performance certification based on regulations developed by the Economic Commission for Europe concerning physical dimensions, tire branding requirements, and high speed endurance.
Eccentric Mounting A condition in which a tire is unevenly mounted or cocked on the hub of a wheel.
Extra Load A P-metric tire with a maximum inflation of 41 psi. This higher pressure than a standard loaded tire permits a greater load capacity.
Extrusion The process of forcing a material through an orifice to obtain a length of material; used to fabricate tire components.
Fabric An array of parrel cords used in tire manufacturing.
Fiberglass A material used in belt construction, consisting of fine spun glass coated with adhesive
Flotation Tire A tire designed to minimize soil penetration and compaction.
Flush Fit A condition where the mounting pad of the wheel goes into place freely and without obstruction against the hub mounting surface.
Follower Joint A non-load-carrying ball joint that maintains the position of the steering knuckle and provides the correct steering axis inclination angle; sometimes called pilot joint or friction joint.
Footprint The mark let by a loaded tire's tread as it comes in contact with the road surface.
Footprint Area The amount or area of contact in square inches the tire has with the road. This is dependent upon both load and inflation pressure as well as tire dimensions.
Fore-and-Aft Weight Transfer A load factor where weight is transferred from the front tires to the rear tires during acceleration and from the rear to the front tires during braking.
Front Wheel Independent-Dead Rear A suspension system found only on front wheel drive cars. It has a solid rear axle which does not transmit driving torque since the car has front wheel drive. It just holds up the rear wheels.
Front Wheel Independent-Live Rear A suspension system found only on rear wheel drive cars. the rear wheels are connected together through an axle which is in turn connected to the frame. A live rear axle includes the differential and transmits driving torque through itself to the rear wheels.
g A unit of acceleration. "g" is a symbol that represents the acceleration of gravity. Acceleration at 1g equals 32 feet per second.
Green Tire A tire which has not been vulcanized or cured.
Grooves Circumferential channels between the tread ribs of a tire.
Grooving A tread cutting process in which grooves of varying depths and angles are cut into a tire's tread to improve forward traction, braking, or lateral stability.
Gross Axle Weight Rating (GAWR) The maximum weight that the front or rear axle can carry. The front and rear gross axle weight must not exceed the front and rear GAWR's.
Gross Combination Weight Rating (GCWR) The total weight of the loaded tow vehicle and the loaded trailer.
Gross Vehicle Weight (GVW) The total weight of the vehicle, including passengers, fuel, cargo and attachments.
Gross Vehicle Weight Rating (GVWR) The maximum permissible loaded weight of the vehicle and takes into account the capabilities of the engine, transmission, frame, spring, brakes, axles and tires. The GVW must not exceed the GVWR.
H-Rated A speed rating category for tires which is used on vehicles with a top speed up to 130 mph.
High Flotation Sizing System for Light Trucks A system using overall diameter in inches, section width in inches, type of tire construction, and rim diameter in inches (e.g.: 33x12.50R15LT).
High Pressure Die Cast A wheel manufacturing process using aluminum, alloys in special high pressure die casting machines.
Hub Centric A situation where the center bore hole of a wheel is made to match up with the hub diameter of the vehicle; the wheel is then centered by the center hole, rather than the lug nuts.
Hydroplaning Loss of traction at high speeds caused by a wedge of water which lifts a tire off the road surface.
Idler Arm A device attached to the frame of the car which duplicated the movement of the Pitman arm and keeps the center link aligned.
Imbalance A non-uniform distribution of mass in a tire and wheel assembly about its axis of rotation.
Independent Suspension A suspension system in which the front or rear pair of wheels of a car are independently connected to the frame or underbody. In this system, deflection of the wheel on one side will not affect the wheel on the other side.
Inertia The tendency of any mass at rest to stay motionless, or any mass which is moving to remain moving in a straight-line.
Innerliner The layers of low permeability rubber which are laminated to the inside of a tubeless tire to insure the air retention quality of the tire body.
Kelnet Firestone's tire design that minimizes stress in tire performance.
Kilopascals (kPa) Unit of air pressure; in metric terms it takes 6.89 kPa to equal 1 p.s.i.
Lateral Runout Wobble or the side-to-side motion of a rotating wheel or tire/wheel assembly.
 

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Authored by: Anonymous on Monday, October 28 2013 @ 03:55 AM EDT Car Talk Terms
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