ASTM_F_1426_-_11.pdf

Designation:F142611Standard Practice forIdentifying Tire Tread Surface Irregular Wear PatternsResulting from Tire Use1This standard is issued under the fixed designation F1426;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of last revision.A number in parentheses indicates the year of last reapproval.Asuperscript epsilon()indicates an editorial change since the last revision or reapproval.INTRODUCTIONOne of the main performance characteristics of tires is the treadlife,defined as the number ofkilometres or miles to wear-out,or where the condition of the tread pattern requires the removal of thetire.Before reaching the condition called“wear-out,”intermediate conditions of treadwear arefrequently encountered,both in tire testing and in normal tire use,that are characterized by complextopological tread pattern features usually called“irregular wear.”When irregular wear is present,certain other tire performance features,such as noise and handling,may fall below acceptable norms.Therefore,it is important in tire development testing and the assessment of tire use performance to beable to describe accurately the condition of the worn surface of tires.Over the years,different descriptive names have been given to these worn tread pattern features.Astandardized nomenclature system is needed to be able to identify the features that are present anddescribe the intensity or magnitude of these features.This practice is intended to give sufficientinstructions to permit an evaluation of irregular wear.To describe adequately the features of thesetread patterns,it is necessary to develop a special logical progressive sequence of definitions ordescriptions.1.Scope1.1 This practice provides the instructions and nomenclatureto evaluate the wear features of the tread pattern on a tire forsome intermediate state short of total wear out.1.2 A tire may be characterized by certain worn treadpattern conditions that are collectively referred to as“irregularwear”features.Definitions for these features are given in aspecial logical and conceptual sequence.First,basic treadpattern definitions are given.Then,additional tread patterndefinitions directly related to the basic tread pattern definitionsare given.Understanding these secondary definitions requiresthe knowledge of the basic definitions.1.3 Based on the terms of this developed system of treadpattern definitions or descriptions,a set of treadwear descrip-tions is presented that encompasses both regular wear andirregular wear features.1.4 This hierarchical arrangement produces the accurate andconcise definitions needed to evaluate the complex irregularwear conditions of tires.1.5 See Fig.1 for tread pattern features or characteristics.See Fig.2 and Fig.3 for typical illustrations of regular oruniform and irregular treadwear features.2.Significance and Use2.1 This practice fulfills the need for a standardized systemfor identifying and describing the tread pattern features of tiresthat are characteristic of intermediate states of treadwear shortof total wear out.This descriptive capability is especiallyimportant in testing programs devoted to the development ofimproved performance tires.It is also important in assessingand evaluating tires after periods of typical tire usage.3.Elementary Features of Tire Tread Patterns3.1 All tires contain an annular volume of rubber,theoutside surface of which comes into contact with the pavementas a loaded tire rotates in vehicle use.This is defined below asa tread band.If surface voids are introduced into this treadband,the usual configuration of these voids produces ageometric pattern of remaining surface projections or elements,that is,regions of the tread band that contact the pavement,collectively called a tread pattern.4.Tire Inspection4.1 The tread pattern of tires for inspection and evaluationshould be clean and free of debris.Tires may be inspected1This practice is under the jurisdiction of ASTM Committee F09 on Tires and isthe direct responsibility of Subcommittee F09.94 on Terminology.Current edition approved Nov.1,2011.Published November 2011.Originallyapproved in 1993.Last previous edition approved in 2003 as F1426 94(2003).DOI:10.1520/F1426-11.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 unmounted(off a rim),but it is recommended that tires bemounted and inflated to normal recommended inflation pres-sure.4.2 Position the tire to be evaluated in a vertical orientation(that is,the plane of the tire is vertical)on a fixture that permitsrotating the tire.Provide sufficient illumination for viewing thetread pattern.Amovable secondary source of illumination witha light path tangential to the tread surface is often useful forviewing subtle wear features.4.2.1 Observe the entire tread pattern of the tire and recordthe treadwear features of the tire according to the wearnomenclature system as given in Sec