ASTM F1426-94(2003)

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Designation:F1426–94 (Reapproved 2003)
Standard Practice for
Identifying Tire Tread Surface Irregular Wear Patterns
Resulting from Tire Use
This standard is issued under the fixed designation F1426; 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.
INTRODUCTION
One of the main performance characteristics of tires is the treadlife, defined as the number of
kilometres or miles to wear out, that is, to the disappearance of the tread pattern. Before reaching the
condition called“ wear out,” intermediate conditions of treadwear are frequently encountered, both in
tire testing and in normal tire use, that are characterized by complex topological tread pattern features
usually called “irregular tire 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 be able 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.A
standardized nomenclature system is needed to be able to identify the features that are present and
describe the intensity or magnitude of these features. This practice is intended to give sufficient
instructions to permit an evaluation of irregular treadwear.To describe adequately the features of these
tread patterns, it is necessary to develop a special logical progressive sequence of definitions or
descriptions.
1. Scope 1.4 This hierarchical arrangement produces the accurate and
concise definitions needed to evaluate the complex irregular
1.1 Thispracticeprovidestheinstructionsandnomenclature
wear conditions of tires.
to evaluate the wear features of the tread pattern on a tire for
1.5 See Fig. 1 for tread pattern features or characteristics.
some intermediate state short of total wear out.
See Fig. 2 and Fig. 3 for typical illustrations of regular or
1.2 A tire may be characterized by certain worn tread
uniform and irregular treadwear features.
pattern conditions that are collectively referred to as “irregular
wear” features. Definitions for these features are given in a
2. Significance and Use
special logical and conceptual sequence. First, basic tread
2.1 This practice fulfills the need for a standardized system
pattern definitions are given. Then, additional tread pattern
for identifying and describing the tread pattern features of tires
definitions directly related to the basic tread pattern definitions
that are characteristic of intermediate states of treadwear short
are given. Understanding these secondary definitions requires
of total wear out. This descriptive capability is especially
the knowledge of the basic definitions.
important in testing programs devoted to the development of
1.3 Based on the terms of this developed system of tread
improved performance tires. It is also important in assessing
pattern definitions or descriptions, a set of treadwear descrip-
and evaluating tires after periods of typical tire usage.
tions is presented that encompasses both regular wear and
irregular wear features.
3. Elementary Features of Tire Tread Patterns
3.1 All tires contain an annular volume of rubber, the
outside surface of which comes into contact with the pavement
This practice is under the jurisdiction ofASTM Committee F09 on Tires and is
as a loaded tire rotates in vehicle use. This is defined below as
the direct responsibility of Subcommittee F09.94 on Terminology.
a tread band. If surface voids are introduced into this tread
Current edition approved July 15, 1994. Published September 1994. Originally
band, the usual configuration of these voids produces a
approved in 1993. Last previous edition approved in 1999 as F1426 – 94 (1999).
DOI: 10.1520/F1426-94R03. geometricpatternofremainingsurfaceprojectionsorelements,
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
F1426–94 (2003)
FIG. 1 Tread Pattern Characteristics
4.3 There are two options for recording the observed tread
pattern features:
4.3.1 Option 1—Record all of the features observed on the
tread pattern, or
4.3.2 Option 2—Record all of the features observed on the
tread pattern with a qualitative indication of the magnitude or
intensity of each feature. Recommended qualifiers are: slight,
moderate, or severe.
FIG. 2 Uniform or Regular Wear
that is, regions of the tread band that contact the pavement, 5. Basic Definitions of General Tread Pattern Features
collectively called a tread pattern.
5.1 tread band, n— an annular volume of rubber that
encompasses the outer pavement contacting periphery of a tire;
4. Tire Inspection
thewidthisnormallymuchgreaterthanthethickness,andboth
4.1 The tread pattern of tires for inspection and evaluation
of these dimensions vary with tire size.
should be clean and free of debris. Tires may be inspected
5.2 void, n—a volume (in the tread band) defined by the
unmounted (on a rim), but it is recommended that tires be
lack of rubber; the depth dimension of this volume may vary
mounted and inflated to normal recommended inflation pres-
from point to point in (on) the tread band.
sure.
5.3 groove, n—a void that is relatively narrow compared to
4.2 Position the tire to be evaluated in a vertical orientation
its length.
(that is, the plane of the tire is vertical) on a fixture that permits
5.4 projection, n— a pavement contacting area of the tread
rotating the tire. Provide sufficient illumination for viewing the
band bounded by void.
tread pattern.Amovable secondary source of illumination with
a light path tangential to the tread surface is often useful for
6. Definitions of Subclassifications of Basic Tread Pattern
viewing subtle wear features.
Features
4.2.1 Observe the entire tread pattern of the tire and record
the treadwear features of the tire according to the wear 6.1 Grooves are major features that may be characterized as
nomenclature system as given in S
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