B”H ASTM F Information 1 ASTM P-Metric-LT Temperature Models Leighton Spadone and Jason Bokar ASTM F Committee Light Vehicle Flat-to-Curved Temperature Tire Society Conference 25 September 2007 Flat vs Curved Contact Surfaces Effect on Consumer Light Vehicle Tire Operating Temperatures

B”H ASTM F Information 2 Tread Act DOT-NHTSA Action: –FMVSS139 Increased Severity Tire Test Standards compared to FMVSS109. Stepped Endurance Test effective Sep2007 Non-Representative Tire Removal Reasons ASTM Response to NHTSA: –The ASTM F09.30 Flat-to-Curved Equivalent- Temperature Task Group Committee should provide technically based information on tire running temperatures to support tire test rulemaking.

B”H ASTM F Information 3 What’s the Problem Consumer Tires operate on a Flat Surface but NHTSA tests require an industry standard, 1.7 meter diameter, Curved Surface. Increased Curved Surface Stresses may lead to atypical tire removals.

B”H ASTM F Information 4 Objective Determine FMVSS130 Curved Surface temperatures their equivalent Flat Highway conditions and temperatures.

B”H ASTM F Information 5 Flat Surface 100% load, 100% infCurved Surface 100% load, 100% inf Wheel Curvature Effect on Tire Deflection. Increased Deflection and three Curved Surface inflection points vs a Single Flat inflection point

B”H ASTM F Information 6 Curvature Effect on Footprint Pressure SURFACE = FLAT 2 Bar & 1056 Kg peak pressure ~5.9 Bar peak pressure ~8.6 Bar SURFACE = 1.7 meter diameter Bar -21% Footprint length +21% Mean shoulder footprint pressure +40% Maximum shoulder footprint pressure

B”H ASTM F Information 7 What We Want to Communicate about Curved Surface Stresses at equal Conditions. Increased Flex Cycles Reduced Footprint Increased Pressure Increased Tire Temperatures Increased Flex Cycles Increased Deflection Reduced Footprint Increased Pressure

B”H ASTM F Information 8 Assumption Tire Running Temperatures are a result of the Operating Conditions as reflected through the tire Construction and Materials response to Operating Conditions Stress. Tire Construction Dimensional Stress Load Inflation Speed Tire Running Temperature Tire Materials Ambient Temperature Surface Curvature Tire Operating ConditionsModeling

B”H ASTM F Information 9 Challenge Communicate Flat-to-Curved Temperature Changes Tire Temperature Statistical Models

B”H ASTM F Information 10 Iterative Action Plan DOE and Test Tire Selection Measure Tire Temperatures on Flat and Curved Surfaces Model and Predict Tire Temperatures Determine Flat-to-Curved Effects in terms of Tire Temperature and Operating Conditions

B”H ASTM F Information 11 Thermocouple Locations Belt Edge was primary Hot Spot

B”H ASTM F Information 12 Tire Thermocouple Test Environment Highway Test Track Flat Track Curved Wheel

B”H ASTM F Information 13 Experimental Steps Phase I & 2: –Thermocouple, Test, and Model the ASTM Tire Sizes –Validate ASTM Phase 1&2 Model with RMA dataset. Phase 3: –Expand Range of Sizes and Types to Generalize Model –Increase model size and stability –Add Centerline couple to model as secondary Hot Spot

B”H ASTM F Information 14 Tire Temperature Model Factors

B”H ASTM F Information 15 Experimental Factors Space

B”H ASTM F Information 16 ASTM Tire Belt Edge Temperature Model SAS JMP Regression Modeling Fit=.95 for the 255 observations available

B”H ASTM F Information 17 ASTM Tire Belt Edge Temperature Model %LF, %SR, and %INF are the most important predictors and account for more that 70% of the Fit. The effect of Ambient Temperature is curvilinear. Collinear Predictors –The MPH and %SR pair and the Const and NS_MM pair may be exchanged to produce slightly different models with similar fit.

B”H ASTM F Information 18 ASTM Hot Spot Models Summary  Communicate Model Implications

B”H ASTM F Information 19 Sixteen Sizes Modeled

B”H ASTM F Information 20 FMVSS139 Flat-to-Curved Equivalent Conditions Adjust the FMVSS139 curved test conditions to produce temperatures equal Flat Highway temperatures generated at the original conditions.

B”H ASTM F Information 21 Situation Running Highway conditions on the wheel will increase the tires temperature due to the higher curved Roadwheel stress. How should Highway conditions be adjusted when run on the curved wheel, to produce tire running temperatures approximately equal to the original Highway condition?

B”H ASTM F Information 22 Adjust Curved Conditions to equal Flat Original Conditions Minus 10% Load and Plus 10% MPH

B”H ASTM F Information BE Flat-Curved DegC Tread Depth NS MM Zero ΔTemperature Curved-to-Flat Load & Inflation Pressure Solution by FMVSS139 Step Hotter Highway Hotter Roadwheel Step1: 75%LOAD 85%INF Step 2-3: 80/90%LOAD 85%INF Step4: 90%LOAD 68%INF

B”H ASTM F Information 24 Flat=Step4: 100%Load 58% INF Flat Belt Edge Temperature for each FMVSS139 Step Conditions Flat=Step3: 100%Load 75% INF Flat=Step2: 100%Load 75% INF Flat=Step1: 100%Load 75% INF

B”H ASTM F Information 25 Summary Other Temperature Equivalence solutions are possible but a simple, consistent adjustment was chosen. Curved Condition Adjustment for 75 MPH FMVSS139Test: Minus 10% Load and Plus 10% Inflation

B”H ASTM F Information 26 FMVSS139 Curved-to-Flat Conditions Equivalency Translate FMVSS139 Curved Conditions to Flat Highway Conditions at Equal Temperatures

B”H ASTM F Information 27 Flat Speed FMVSS139 Step Conditions %LOAD and %INF are Unchanged

B”H ASTM F Information BE Flat -Curved DegC Tread Depth NS MM Zero ΔTemperature Flat-to-Curved Speed Solution by FMVSS139 Step Step1-2: MPH Solution Step 3-4: MPH Solution Hotter Flat Hotter Roadwheel

B”H ASTM F Information 29 FMVSS139 Belt Edge Temperature by Step Step4: 100%Load 58% INF Step3: 100%Load 75% INF Step2: 90%Load 75% INF Step1: 100%Load 75% INF

B”H ASTM F Information 30 Summary The Tire Running Temperature was Statistically Modeled as a function of Speed, Load, and Inflation with adjustments for Ambient Temperature, Deflection, and a Construction Index.

B”H ASTM F Information 31 Conclusions Curved Roadwheel tire testing is more severe than the Flat Highway. Adjustment to the Curved Wheel Conditions to match Flat Highway Temperature is:  -10% Load +10% MPH Highway Speeds of 92 to 98 MPH match the FMVSS139 Step Roadwheel temperatures.