Selection of Tyres for BAJA Vehicle byRajesh MankarManager Product DevelopmentJ K TYRE AND INDUSTRIES LTDSunday, 10th August 2008

Agenda: History, Tyre Definition & Classification

Function of Tyre

Defining Basic Dimensions

Tyre Construction

Tyre selection criteria based on Vehicle info and performance

New Development Approach

1844 Charles Goodyear invented vulcanized rubber that was later used for tires.

1888 John Dunlop invented the air-filled or pneumatic tires for bicycles.

1895 Andr Michelin was the first person to use pneumatic tires on an automobile, however, not successfully.

1901 Philip Strauss invented the first successful tire, which was a combination tire and air filled inner tube.

1903P.W. Litchfield of the Goodyear Tire Company patented the first tubeless tire,

1904Mountable rims were introduced that allowed drivers to fix their own flats.

1908Frank Seiberling invented grooved tires with improved road traction.

1910 B.F. Goodrich Company invented longer life tires by adding carbon to the rubber. History Of Tyre:

What Is Tyre: Geometrically tyre is a torus reinforced with textile cord ply / fabric or steel carcass enclosing bead ring. Mechanically it is a flexible membrane pressure container Structurally it is a high performance composite Chemically a material composed of long chain of macromolecules TYRE SIZE DESIGNATION:

A Tyre is generally designated by its nominal cross section code followed by the nominal rim diameter code.For radial tyres,

145/80R13

Section width (mm) Aspect Ratio Nominal Rim Dia (inch)

Tyre Size Designation:Enveloped Dimension:145/80R13Section Width 145 mmAspect Ratio 80 Rim Diameter 13Outer Diameter = (2 x Section Height in mm) + Rim Diameter in mmSection Height = 145*0.8 = 116 mmOuter Diameter = (2*116) + (13*25.4) =562.2 mm

Basic Tyre Dimensions:Tyre Section

Function Of Tyre: Provide Load Carrying Capacity Provide Cushioning and dampening Transmit driving and braking torque Provide Cornering force Provide floatation and dimensional stability Resist abrasion Generate steering response Have low Rolling Resistance Provide minimum noise and minimum vibration Be durable throughout and expected life spam

Tyre Construction:BIASRADIALTUBE TYPETUBELESSContd

Tyre Construction:Cord strips are arranged diagonally to the centerline of the tire.

Positive Qualities - strengthens the sidewall and stabilizes the tread area for contact patch.

Negative Qualities Builds up excessive heat; very stiff and hard riding; get flat spots after sitting in one spot and cooling down.Plies are laid at 90 degree angles to centerline of tire

More sidewall movement and a smoother ride

Last longer than bias ply tiresBIASRADIAL

Tyre Construction:RADIAL

Tyre Construction:BIAS

Tyre Construction:ADVANTAGE OF RADIAL TYRES 50 - 100% LONGER LIFE - REDUCED COST PER KILOMETER 5 - 10% FUEL SAVING PUNCTURE RESISTANT - LESS DOWN TIME RIDING COMFORT AND REDUCED CARGO DAMAGE EXCELLENT HIGH SPEED CAPABILITY EXCELLENT DAMPENING OF VIBRATIONS EXCELLENT TRACTION & BRAKING ON BOTH DRY AND WET ROAD

Tyre Construction:Tubeless TechnologyA tubeless tyre is designed with a Halobutyl liner on the inner side which is applied from bead to bead.

The Bead contour of tubeless tyres are designed to provide a self sealing mechanism between the tyre and rim. Lower Rolling resistance Better handling Characteristics at high speeds It is also reported, that air leakage after puncture is slower in tubeless tyres than tubetype tyres thus making tubeless tyres safer.ADVANTAGE OF TUBELESS TYRES:A tube Type tyre running at reduced pressures generates more heat and is more prone to damage.

A tube type tyre is often easier to repair in the bush than a tubeless one, because they are easier to remove from the rim and are much easier to re- inflate

Tubes do not strengthen the tyre or help prevent punctures.Tube Type

Tyre selection criteria based on Vehicle Application and performance

Passenger CarSUVMUVLight commercial VehicleHeavy commercial VehicleBased on Vehicle Application:

Based on Vehicle Dimensions / Load / Speed:Wheel BaseTreadGround Clearance FAW / RAW Kerb Weight Gross Vehicle Weight Empty Vehicle Weight Pay Load Load Distribution

Tyre Selection Criteria Based on Performance:Safety- Max. driving safety under various conditions (dry, wet, winter, etc.)HandlingTire Characteristics Cornering Economics- Mileage- Rolling ResistanceComfort- Mechanical Comfort (flat spot)- Acoustic Comfort

Effect of component on Tyre Performance:HYSTERESIS LOSS Rubber ASPECT RATIORIM WIDTHTYRE SIZETYRE TYPETREAD PATTERNTREAD RADIUSTREAD THICKNESSTREAD DEPTHCORD ANGLENUMBER OF BODY PLIESCONSTRUCTIONROAD TEXTURE AND ROUGHNESSAERODYNAMIC DRAGNOISEAIR CAVITY PUMPINGINFLATION PRESSUREEFFECT OF SPEEDEFFECT OF LOADEFFECT OF TEMPERATUREEFFECT OF INNER TUBEInternal FactorExternal Factor

Feel the power of FEA SimulationA Simulation showing strain energy Distribution under loadingAn FEA simulation revealing Inter carcass pressure acting Inside the tyrePredictive Methods to Optimize Tyre Design:

Tyres determine to a great extent the dynamic behavior of road vehicles. Our attempt is to assist in bringing optimized synergy between the mechanical characteristics of tyre in contact with the road & the mechanics of the vehicle so that tyre-vehicle system operates safely under any circumstances & in a way that is satisfactory to the driver.Predictive Methods to Optimize Tyre Design:

Force & Moment Test MachineOther Methods to Optimize Tyre Design:

Tyre Selection Criteria Based on Performance:Rolling ResistanceMechanical Energy converted into Heat by a tire moving for a unit distance on the roadway as a result of the rotation and the deformation of the tire

Energy Consumed per unit distance of travel as a tire rolls under load

Resistance to Motion

The amount of energy required overcoming the friction between the tyre and road surface.The RR of a tire is responsible for 14.4% of the total vehicle energy loss.

For passenger and light truck, Improvement in rolling resistance of 10% - Fuel efficiency increased by 0.5 ~ 1.5% and for heavy truck fuel efficiency increased by 1.5 ~ 3.0%Contd

Tyre Selection Criteria Based on Performance:Rolling Resistance

Chart1

48

26

7

7

8

2

2

0

% Contribution

% Contribution to RR

Rolling Resistance Testing Machine

Tyre Selection Criteria Based on Performance:Tyre TractionTraction performance can be characterized in many ways, including braking, acceleration, cornering, controllability, and grade climbing. Though all factors are important, the single best indicator of tire performance is braking distance and deceleration.

PARAMETERTRACTION (WET & DRY)TARGETIMPROVED TRACTION WITHOUTSACRIFICING TREAD LIFEPRIORITYINTERMEDIATEPRIMARY APPROACHTREAD COMPOUND OPTIMIZATIONSECONDARY APPROACHCASING DESIGN OPTIMIZATIONIMPORTANTTO CONTROL TENDENCY OF WANDERING & STEERING PULL WHILE BRAKING OEMs ARE EMPHASIZING THE NEED TO ACHIEVE A STABLE CONTACT PATCH WHICH DOES NOT CHANGE ITS CENTRE DURING BRAKING

Tyre Traction Subjective & Objective Evaluation

Tyre Selection Criteria Based on Performance:Tyre WearFactors affecting Tyre WearImproper Vehicle toe, camber,caster, drive axle parallelism andperpendicularity are important factorstire wear patterns.

PARAMETERTREAD MILEAGE (WEAR)TARGETFURTHER IMPROVEMENT REQUIREDPRIORITYINTERMEDIATEPRIMARY APPROACHTREAD DESIGN / DEPTH OPTIMIZATION

SECONDARY APPROACHTREAD FORMULATION OPTIMIZATIONINCREASED USE OF POLYBUTADIENE AND OPTIMIZED SOLUTION SBR

StructurePressure Imaging and AnalysisPressure MappingPressure ApplicationFoot Print Pressure Distribution study revealed higher pressure at Shoulder blocks than at center.

Fujifilm Footprint pressure distribution studyTyre Wear Predictive Methods:

ThermographyMeasurement of surface temperature in the tyre using a thermo graphic camera and fine tuning the related parameters during the development processMin Temperature 62.69Max Temperature 72.56Min Temperature 58.19Max Temperature 67.58Tyre Wear Predictive Methods:

Cornering Stiffness Testing

Tyre Selection Criteria Based on Performance:Tyre Ride & Handling Performance

PARAMETERRIDE & HANDLING PERFORMANCETARGETFURTHER IMPROVEMENT REQUIREDPRIORITYINTERMEDIATEPRIMARY APPROACHPATTERN DESIGN ENGINEERING (NOISE) CASING DESIGN ENGINEERING (CONSTRUCTION, MATERIALS & CONTOUR IN ORDER OF PRIORITY)

SECONDARY APPROACHTREAD COMPOUND OPTIMIZATION(INITIATION OF VERTICAL ENGINEERING IMPLEMENTATION (VEHICLE & TYRE DESIGNERS WORKING CLOSELY FROM THE INCEPTION STAGE))

Tyre Ride, Comfort & Handling Performance

Tyre Ride, Comfort & Handling PerformanceBreaking StrengthStiffness Test Station

2D - Pattern3D - ModelMarking Hand CarvingTyre testing fitted on vehicleRapid Prototyping

Functional Parameters:Rubber Compound and Chemicals: a) Natural Rubber b) Synthetic Rubber c) Carbon Black d) Silica e) Fabric f) Steel Cords

Functional Parameters:RIB PATTERN : The pattern along the circumference of the tyre Good points : Lower rolling resistance. Good directional stability and steering control thanks to lateral resistance. Suitable for sustained high speeds thanks to low heat generation. Bad points : Poor braking & acceleration grip on wet roads. Stress caused by flex means tread is more susceptible to cracking. Use : For paved road surfaces and the steering wheels of trucks or buses LUG PATTERN : The groove pattern perpendicular to the circumference of the tyre Good points : Excellent braking & driving power. Superior traction. Bad points : Noisy at high speed. It's not suitable for high speed driving because of high rolling resistance. Uses : For dirt roads, rear wheels of buses, industrial vehicles and dump trucks . Tread Pattern:

Functional Parameters:Tread Pattern:SEMI-LUG PATTERN : The combination of Rib-shape & Lug-shape Features : The rib in the centre provides directional control whilst the shoulder lug gives good braking & driving power. Uses : Good for both paved and dirt roads. Usually used in both front & rear wheels of trucks and buses. BLOCK PATTERN : The pattern of independent block which the groove is connected with each other Good points : Good steering control and stability on snow covered and wet roads. Good water dispersal properties on wet roads. Bad points : Tyre wear is heavy as tread blocks are finer. Uses : Suitable for winter or all-season passenger car tyres. Suitable for back-wheel of Radial tyre of ordinary car .

Functional Parameters:Tread Pattern:ASYMMETRIC PATTERN : Tread pattern differs on either side Good points : Good for high speed cornering thanks to greater contact area. Reduces tread-wear on outside of tyre. Bad points : You must position them the right way around. Uses : High performance and motorsport tyres. DIRECTIONAL PATTERN : Lateral grooves on both sides point the same direction. Good points : Good driving force and braking performance. Good water dispersal means good stability on wet roads. Correct choice for fast driving styles. Features : mounted in direction of tread pattern. Uses : the passenger car tyre for high speed usage.

Functional Parameters:TreadBelt and BreakersCap Ply/ Prot Ply CarcassSide WallBeadChaferFillerTyre Components:

Functional Parameters:Tread

Tread is the wear resistance component of the tyre, when it is contacting with the road. It must also provide traction, wet skid and good cornering characteristics with minimum noise generation and low heat buildup. It is the part through which braking, driving and cornering forces are transmitted.These are short plies of rubber coated steel cut at an angle and are positioned centrally between the tyre casing and tread to strengthen carcass against impacts.BeltsCap PlyIt is placed in the crown area just below the tread rubber. It provides cut resistance protection to the underlying belts and carcass plies.Enhances high-speed suitability.

Functional Parameters:Carcass

Rubber bonded cord structure of a tyre integral with the bead, which provides the required strength to carry load.SidewallPart of the tyre between bead and tread which flexes in service. Protects the casing from side scuffing, control vehicle and ride characteristics and assist in tread supportBead CoreA bead should hold the tyre against the rim and should avoid the movement of the tyre relative to rim. The shape and contour of the bead conforms to the flange of the rim, thus preventing from rocking or slipping on to the rim.

Functional Parameters:Filler

Chafer

Gives steering precisionImproves comfortTo prevent chafing action between bead and rim. Their purpose is to protect the carcass plies from damage when mounting or dismounting and to reduce the effects of wear and chafing between the wheel and thetire bead

Thank You rajeshmankar@jkmail.com 09971492958