ASTM_F_762_-_F_762M_-_08_2014.pdf

Designation:F762/F762M08(Reapproved 2014)Standard Test Method forDetermining Change in Groove(or Void)Depth WithDistance Traveled for Passenger Car Tires1This standard is issued under the fixed designation F762/F762M;the number immediately following the designation indicates the yearof original adoption or,in the case of revision,the year of last revision.A number in parentheses indicates the year of last reapproval.A superscript epsilon()indicates an editorial change since the last revision or reapproval.1.Scope1.1 This test method covers a procedure to be used to obtaindata for determining the changes in tire tread depth over anyspecified course and test period.1.2 The tire tread depth loss data obtained according to theprocedures for this test method may be used to calculate tiretread wear by way of the procedures described in PracticeF1016.1.3 The values stated in either SI units or inch-pound unitsare to be regarded separately as standard.The values stated ineach system may not be exact equivalents;therefore,eachsystem shall be used independently of the other.Combiningvalues from the two systems may result in non-conformancewith the standard.1.4 This standard does not purport to address all of thesafety concerns,if any,associated with its use.It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2.Referenced Documents2.1 ASTM Standards:2F421 Test Method for Measuring Groove and Void Depth inPassenger Car TiresF457 Test Method for Speed and Distance Calibration ofFifth Wheel Equipped With Either Analog or DigitalInstrumentationF538 Terminology Relating to the Characteristics and Per-formance of TiresF1016 Practice for Linear Tire Treadwear Data AnalysisF1502 Test Method for Static Measurements on Tires forPassenger Cars,Light Trucks,and Medium Duty Vehicles3.Terminology3.1 Definitions:3.1.1 break-in,none or more periods of initial standard-ized tire operation during which tire is brought to the statewhich will lead to more consistent test results.F5383.1.2 element,nan isolated(totally bounded by void)projection.F5383.1.3 groove,na void that is relatively narrow comparedto its length.F5383.1.4 groove(void)average depth,nthe average depth ofall groove depth measurements in a single groove.F5383.1.5 groove(void)depth,L,na measurement of theperpendicular distance from a real or calculated reference planedefined by edges of two adjacent ribs or elements to the lowestpoint of contact in the groove(void).F5383.1.6 irregular wear,na type of treadwear characterizedby substantial variations of tread loss both from projection toprojection and frequently from point to point on a givenprojection.F5383.1.7 measurement interval,nthe distance travelled,inkilometres miles,between two successive groove(void)depth measurements.F5383.1.7.1 DiscussionA specified number of test cycles willconstitute a measurement interval.If a tire rotation plan isspecified,the measurement interval shall include equal dis-tance on each specified wheel position for each tire testspecimen.More frequent measurements may be made ifdesired.The number of measurement intervals should becompatible with the tire rotation plan to result in a logical basisfor data interpretation.3.1.8 projection,na pavement contacting area of the treadband,bounded by void.F5383.1.9 rib,na continuous circumferential projection.F5383.1.10 rotation plan,n in tire testing,the scheduledchange of wheel positions for all tires on a vehicle,andbetween vehicles in a convoy,and scheduled change of vehicleposition in a convoy during a road test as appropriate.F5383.1.10.1 DiscussionTest tires should occupy each positionon the vehicle for the same number of cycles.A tire rotation1This test method is under the jurisdiction of ASTM Committee F09 on Tiresand is the direct responsibility of Subcommittee F09.30 on Laboratory(Non-Vehicular)Testing.Current edition approved June 1,2014.Published November 2014.Originallyapproved in 1982.Last previous edition approved in 2008 as F762/F762M 08.DOI:10.1520/F0762_F0762M-08R14.2For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM Customer Service at serviceastm.org.For Annual Book of ASTMStandards volume information,refer to the standards Document Summary page onthe ASTM website.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 plan may be designed for each test in accordance with therequirement of the test program.3.1.11 test cycle,nin tire testing,one complete circuit ofthe specified test course.F5383.1.12 tread depth average,n in a single tire,the averageof all tire groove(void)depth measurements.3.1.13 void,na volume(in the tread band)defined by thelack of rubber;the depth dimension of the volume may varyfrom point to point in(on)the tread band.F5384.Summary of Test Method4.1 The tire test procedure is carried out by repeatedlydriv