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Abstract
Deflection-MPH: Predict Off-The-Road Tire Deflection and Temperature

Introduction:
A mine site's two largest operational costs are vehicle fuel and tires. Tire longevity is improved by limiting tire temperatures to the manufactures guidelines by limiting the tire's combination of speed, load, and inflation.

Deflection is the tire section height decrease as can be measured from the center of the tire rim to the road surface due to a tire Load at a tire Inflation pressure. Deflection is a function of the tire load & inflation combination.

Predicting radial OTR Tire deflection and footprint dimensions reduces deflection-testing needs and the response time for deflection feedback. Model predictions can provide data across a wide range of loads and inflations that are not normally tested.

Measuring deflection simplifies and accurately reflects the tire load and inflation that is needed to Model the Tire's Equilibrium Running Temperature and Deflection.

Benefits:
Predicting tire deflection and footprint dimensions, allows tire footprint dimension optimization to meet vehicle requirements at an early design stage, before investment in molds and tire production.

Modeling Tire Deflection and Tire Running Temperatures provides an accurate methodology, Deflection-MPH, to predict tire overheating.

At mine sites, TMPH calculations use estimates of tire load based on assumptions of vehicle weight, haul load and load distribution to each tire and assumptions about each tire's inflation pressures. Errors in these estimates can lead to tires being over-deflected and generating running temperatures that exceed their manufacturer's recommendations. The TMPH equation is not predictive of tire equilibrium running temperature.

The ability to model tire deflection and running temperatures allows the implementation of Deflection-MPH equations that can match tire running temperature to vehicle service conditions in order to limit tire overheating and heat related failures and removals.

Predict OTR Tire Deflection

Introduction:
A mine site's two largest operational costs are vehicle fuel and tires. Tire longevity is improved by limiting tire maximum temperatures to the manufactures guidelines by balancing the tire's operational speed, load, and inflation combinations. Maximizing mine profits depends on balancing tire replacement and vehicle downtime costs vs. tonnage and profits.

The mining account vehicle work cycle consists of a loaded and empty round trip cycle. The Job or Vehicle TMPH is defined as the average, loaded plus empty, vehicle load in Tons multiplied by the average speed in MPH. The individual tire inflations and individual tire loads are not included in the TMPH calculations, only the vehicle total loads. Therefore, TMPH assumes each individual tire load and inflation is correct. Further, the TMPH equation is not predictive of tire running temperatures.

It is the tire's deflection, as it rotates thought the tread footprint area & MPH, which causes the tire to flex, compress, and generate heat. The tire heat build-up is due to Deflection-MPH and so Deflection-MPH, is the actual limiting factor for a tire's actual heat performance. The individual tire's running temperature is critical to tire longevity.

The Challenge:

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Leighton Spadone, President of DAAS Inc., has over 50 years of Tire Technology and Applied Statistics experience. He trains and consults tire companies on Tire Design, Tire Materials and Compound Formulations, Tire Curing, rubber processing, quality control, tire, compound, and materials testing. Mr. Spadone was employed by Goodyear Tire & Rubber Co in International Technical Service and Domestic Tire Development for over 43 years and by Eurotire Inc for 6 years as the Chief Technical Officer. he is an experienced Materials Product Developer for Radial Light Truck Tires, Radial Medium Truck Tires, Farm Tires, and Off-Road Radial Earthmover Tires.

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