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Tire Design, Manufacturing and Performance Considerations. CIWMB Market Development and Sustainability Committee Sacramento, CA September 12, 2007. North America. RMA Tire Company Members. RMA Tire Company Representatives Here Today:. Presentation Outline. Tire Performance Overview
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Tire Design, Manufacturing and Performance Considerations CIWMB Market Development and Sustainability Committee Sacramento, CASeptember 12, 2007
North America RMA Tire Company Members
Presentation Outline • Tire Performance Overview • Mike Wischhusen, Michelin North America • Governmental Requirements • Dan Guiney, Yokohama Tire Corporation • Tires, Tire Tread Wear and Vehicle Fuel Economy • Sim Ford, The Goodyear Tire and Rubber Co. • Recycled Content and New Tires • Don Amos, Continental Tire North America • Conclusions • Tracey Norberg, RMA
Section 1:Tire Performance OverviewMike WischhusenMichelin North America
A round shape made from rubber Is it that simple ? The hidden side of the tire
Tread band and tread pattern Separating rubber Crown structure: Nylon belt pliesSteel belt plies Casing ply Sidewall Casing ply turn-up Reinforcement Heel-shaped anchorage to the rim Bead wire Inner liner The hidden side of the tire A tire also contains hidden complexity
150 cm2 500 cm2 = 1 HAND = 3 HANDS The tire: your only contact with the ground At the steering wheel, the only thing linking you to the road is the tire.
Grip and road handling: carry roll 1 1 steer 2 2 3 3 Obeying the driver's orders:
1 The tire pushes the water out towards the sides 1 1 1 2 2 2 2 The tire's tread dries the road. 3 3 3 3 The ribs in the tread pattern cut through the residual film of water. Traction on Wet Surfaces
Axis of wheel direction Axis of trajectory Skid angle Thrust of ground Contact patch Vehicle Handling A tire under great stress: - steering - acceleration - braking
The wear life span depends mainly on the rolling conditions STATISTICAL DISTRIBUTION OF LIFE SPANS Rolling conditions Number of cases in sample observed severe normal gentle Very gentle WEAR = loss of tread depth as the mileage rises miles 20 000 40 000 60 000 80 000 Working in the long term
Working in the long term Endurance 60 miles per hour means 10 – 15 revolutions per second, or 20 to 30 deformations per second (20 – 30 Hz)
Constant improvements in comfort Mechanical and acoustic comfort Obstacle on the road: noise and vibrations Measurement of noise when a vehicle passes
Constant improvements in comfort Acoustic comfort Rectilinear impact front: all the tread blocks across the width of the tire enter into contact with the ground at the same time. Rolling direction Tread blocks with irregular orientation = noise reduction Tire with 3 patternsizes
Average Consumer Rolling resistance Rotational direction Energy loss due to deformations
energy loss energy loss No energy loss PERFECTLY ELASTIC MATERIAL HIGH HYSTERESIS MATERIAL LOW HYSTERESIS MATERIAL Reduce Rolling Resistance Increase Traction Rubber Compounds
Rolling Resistance and Hysteresis 60 mph means 10-15 deformations per second, 10-15 Hz.
Grip and Hysteresis The surface deformation responsible for grip occurs at frequencies between 103 and 1010 Hz
RR, Grip and Hysteresis HYSTERESIS Energy Dissipation Rolling ResistanceRange Grip Range 10 100 1000 10000 100000 FREQUENCY Hz (log scale)
RR, Grip and Hysteresis HYSTERESIS Energy Dissipation Rolling ResistanceRange Grip Range 10 100 1000 10000 100000 FREQUENCY Hz (log scale)
Coefficient of rolling resistance in kg/t Solid tires 30 25 20 15 10 5 0 First pneumatic tires Car tires Truck tires Train wheels on track Metro tiresTires for Shell Eco Marathon First steel belted tires First radial tires Green X First metallic tires Energy 3 Energy 1880 1900 1920 1940 1960 1980 2000 2020 Orders of magnitude in 2002 : • Tires for cars : 8,5 à 13 kg/t • Tires for trucks : 4,5 à 10 kg/t - Tires for bicycles : 2,5 à 5 kg/t Consuming less Rolling resistance
The art of balance Car tires
Section 2: Governmental RequirementsDan GuineyYokohama Tire Corporation
U.S. Government Requirements • Performance Standards • Passenger Tires – Federal Motor Vehicle Safety Standard (FMVSS) 109 – will be changing to 139 in September 2007 • Commercial Tires – FMVSS 119 – also being revised; proposal expected soon • Tire Labeling – specifications for information on tire sidewall
U.S. Government Requirements • Consumer Information Requirements • Uniform Tire Quality Grading • Traction, Tread Wear, Temperature • Applies to same tires as AB 844 • Early Warning Reporting – vehicle and component manufacturers required to report production, warranty and property damage claims, injuries and fatalities to NHTSA
Compliance with US Governmental Requirements • Compliance with federal requirements demonstrated through self-certification of product • NHTSA conducts compliance audits of sample of tires each year to assess compliance • Companies also self-report if compliance or defect issue is discovered with a particular tire • Companies conduct voluntary consumer satisfaction programs and mandatory recalls if necessary
Tire Testing / Grading • Uniform Tire Quality Grade – 49 CFR §575.104 • TreadwearComparative rating based on wear rate of the tire when tested under controlled conditions on a specified government test course. • TractionRated AA, A, B, C. Grades represent the tire’s ability to stop on wet pavement as measured under controlled conditions on specified government test surfaces. • TemperatureRated A, B, C. Grades represent the tire’s resistance to the generation of heat and its ability to dissipate heat when tested under controlled conditions on a specified indoor laboratory test wheel.
International Governmental Requirements • Europe • Japan • Saudi Arabia • Other Countries (India, China, Brazil, Australia, Mexico, Peru, etc.)
Customer Requirements • Tire industry must also meet exacting customer requirements • Original equipment (auto company) customers typically interested in low rolling resistance, ride, handling, noise, comfort • Replacement market customers interested in long tread life, traction and price
Section 3: Tires, Tire Tread Wear and Vehicle Fuel EconomySim FordThe Goodyear Tire & Rubber Company
Environmental Considerations in the Design Process • Tire materials content issues • Manufacturing emissions issues • Toxicity issues • Worker health and safety issues • Tire rolling resistance and vehicle fuel economy • Tread wear miles and scrap tire generation
California Interests • California Energy Commission addressing “tire efficiency” – tire rolling resistance and vehicle fuel economy • RMA is working closely with CEC on implementation of AB 844 • CIWMB addressing scrap tire issues • RMA is committed to working with CIWMB on these issues • Tire rolling resistance and tire tread life are interrelated tire performance properties • Key is to balance interest in improving vehicle economy with interest in longer wearing tires, so as not to create unintended consequences
Tire Rolling Resistance • Tire rolling resistance is the tire’s contribution to vehicle fuel economy • The lower the tire rolling resistance, the more fuel efficient the vehicle will be, all other things being equal • Tire rolling resistance is affected by: • Tire design and construction • Rubber compounds • Tire inflation pressure • Roadway surface • Vehicle alignment
Rolling Resistance Trade-Offs Improved compound and construction technologies can minimize performance trade-offs. Expect potential trade-offs in dry traction and wear.
Rolling Resistance Impact on Fuel Consumption Fuel energy is dissipated in many ways, including rolling resistance: A 10% improvement in rolling resistance gives a 1-2% improvement in fuel economy National Research Council, "Automotive Fuel Economy: How Far Should We Go?", 1992)
Rolling Resistance Impact on Fuel Consumption U.S. Department of Energy – “Energy Technology and Fuel Economy” - Typical energy losses in city driving.
Rolling Resistance Impact on Environment • Improved rolling resistance performance reduces vehicle fuel usage • 1-2% for every 10% improvement in tire rolling resistance • Poor tire inflation maintenance negates tire design benefits • Improved rolling resistance decreases tire wear life, so more tires are required for the same miles • More raw materials, more energy to produce and bring to market • Increased scrap tires
Longer Tread Wear Tires • Tires can also be designed to optimize tread wear potential for longer-wearing tires • Tire tread life is affected by • tire design • tread compound • tire inflation • roadway surfaces • vehicle (size, aerodynamics, loads, alignment) • driver (aggressiveness, maintenance habits)
Longer Tire Tread Wear Trade-Offs Design trade-offs usually mean reduction in some characteristics to improve others Tire wear improvements generally require reduced rolling resistance and traction
Average Tire Mileage 1980 - 2003 * excludes light truck and SUV fitments Source: Consumer Panel of Vehicle Owning Households
Longer Life Tires Impact on Environment • Improving tire tread life • Reduces number of scrap tires • Improves customer satisfaction • Reduces fuel economy • Reducing tire tread life • Increases materials and energy required to produce and bring tires to market • Increases number of scrap tires • Poor tire maintenance reduces tread life
Tire Inflation Pressure – An Environmental Issue! • Vigilant tire inflation pressure maintenance improves vehicle fuel economy and prolongs tire tread life • Properly inflated tires have lower rolling resistance than when under inflated • Tires underinflated by 7 psi will achieve 1-2% reduction in vehicle fuel economy; effects are even greater with lower inflation pressures (TRB, 2006) • Under inflated tires achieve fewer tread miles due to uneven tread wear caused by the underinflation
NHTSA Air Pressure Study • Independent study commissioned by NHTSA in February 2001 • Tire pressure measured on 11,530 vehicles • 6,442 passenger cars • 1,874 SUVs • 1,376 vans • 1,838 pickup trucks • Tire pressures measured ‘hot’ • Survey of drivers
NHTSA Air Pressure Study • 3% of passenger cars and 6% of light truck vehicles have all four tires significantly underinflated • 27% of passenger cars and 33% of light trucks have at least one tire significantly underinflated • And these tires were measured ‘hot’!