ASTM F538-22

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Designation: F538 − 21 F538 − 22
Standard Terminology Relating to
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Characteristics and Performance of Tires
This standard is issued under the fixed designation F538; the number immediately following the designation indicates the year of 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. Scope*
1.1 This terminology primarily covers definitions for technical terms that occur in ASTM Committee F09 standards on the
characteristics and performance of tires.
1.2 Definitions for terms that may also be used in other technologies, such as vehicle behavior, are worded to cover both areas.
1.3 When any definition in this terminology (that does not have the limiting phrase) is quoted out of context, editorially insert the
limiting phrase in a tire after the dash following the term. This will properly limit the field of application of the term and definition.
1.4 This international standard was developed in accordance with internationally recognized principles on standardization
established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued
by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
2. Terminology
2.1 Definitions:
accelerometer, n—an instrument that senses inertial reaction to measure linear or angular acceleration. F811
accuracy, n—a measurement concept that describes the degree of correspondence between an average measured value and an
accepted reference or standard value for the object, material or phenomenon under test.
age, v—to apply conditions so as to promote change of material properties. F2838
aging, accelerated laboratory (also: aging, laboratory), n—increased rate of tire material property changes under specified
conditions, including temperature, inflation pressure, oxygen concentration in the filling gas, and time. F2838, F3015
aging, in-service, n—material property changes within tires due to consumer usage. F2838, F3015
aging, oven, n—accelerated laboratory aging in an elevated temperature environment. F2838, F3015
aging, thermal oxidative, n—the process whereby chemical and physical material properties of a tire change with exposure to
heat and oxygen. F2838
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This terminology is under the jurisdiction of ASTM Committee F09 on Tires and is the direct responsibility of Subcommittee F09.94 on Terminology.
Current edition approved April 1, 2021Oct. 1, 2022. Published May 2021October 2022. Originally approved in 1977. Last previous edition approved in 20132021 as
F538 – 13.F538 – 21. DOI: 10.1520/F0538-21.10.1520/F0538-22.
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
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F538 − 22
aligning stiffness [FL/γ], n—of a tire, the rate of change of tire aligning torque with respect to change in tire slip angle, usually
evaluated at zero slip angle.
aligning stiffness coefficient, n—of a tire, the ratio of tire aligning stiffness to the tire normal force.
aligning torque [FL],n—of a tire, the component of a tire moment vector tending to rotate a tire about the Z'-axis, positive
clockwise when looking in the positive direction of the Z'-axis. F424
alignment, n—the adjustment of various parts of the vehicle’s suspension system to ensure proper handling stability and to
minimize abnormal tire treadwear. F1922
all-season tread, n—tread design providing dry, wet, and snow traction performance for an optimized balance for year-round
performance and which may meet the U.S. Tire Manufacturers Association (USTMA) definition for an M&S, M+S, M/S, MS,
etc. marked tire (see USTMA “Snow Tire Definitions for Passenger and Light Truck (LT) Tires”). E1136, F2493
alternate element wear, n—type of element wear characterized by a pattern of an increased wear rate on alternating isolated
projections; the wear may be every second projection, every third projection, every fourth projection, etc. or a combination
thereof. F1426
analysis, n—an act of inspecting a shearographic or holographic (S/H) system image and associating this image with a known
calibration reference. F1364
anomaly, n—a change in the strain pattern of the rubber surface of a straining block as a result of applied stress brought about
through a change in atmospheric pressure on the r
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