ASTM F1426-94(1999)

NOTICE: This standard has either been superceded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
Designation: F 1426 – 94 (Reapproved 1999)
Standard Practice for
Identifying Tire Tread Surface Irregular Wear Patterns
Resulting from Tire Use
This standard is issued under the fixed designation F 1426; 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 (e) 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 1.5 See Fig. 1 for tread pattern features or characteristics.
See Fig. 2 and Fig. 3 for typical illustrations of regular or
1.1 This practice provides the instructions and nomenclature
uniform and irregular treadwear features.
to evaluate the wear features of the tread pattern on a tire for
some intermediate state short of total wear out.
2. Significance and Use
1.2 A tire may be characterized by certain worn tread
2.1 This practice fulfills the need for a standardized system
pattern conditions that are collectively referred to as “irregular
for identifying and describing the tread pattern features of tires
wear” features. Definitions for these features are given in a
that are characteristic of intermediate states of treadwear short
special logical and conceptual sequence. First, basic tread
of total wear out. This descriptive capability is especially
pattern definitions are given. Then, additional tread pattern
important in testing programs devoted to the development of
definitions directly related to the basic tread pattern definitions
improved performance tires. It is also important in assessing
are given. Understanding these secondary definitions requires
and evaluating tires after periods of typical tire usage.
the knowledge of the basic definitions.
1.3 Based on the terms of this developed system of tread
3. Elementary Features of Tire Tread Patterns
pattern definitions or descriptions, a set of treadwear descrip-
3.1 All tires contain an annular volume of rubber, the
tions is presented that encompasses both regular wear and
outside surface of which comes into contact with the pavement
irregular wear features.
as a loaded tire rotates in vehicle use. This is defined below as
1.4 This hierarchical arrangement produces the accurate and
a tread band. If surface voids are introduced into this tread
concise definitions needed to evaluate the complex irregular
band, the usual configuration of these voids produces a
wear conditions of tires.
geometric pattern of remaining surface projections or elements,
that is, regions of the tread band that contact the pavement,
collectively called a tread pattern.
This practice is under the jurisdiction of ASTM Committee F-9 on Tires and is
the direct responsibility of Subcommittee F09.94 on Terminology.
Current edition approved July 15, 1994. Published September 1994. Originally
published as F 1426 – 93. Last previous edition F 1426 – 93.
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NOTICE: This standard has either been superceded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
F 1426 – 94 (1999)
FIG. 1 Tread Pattern Characteristics
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.
5. Basic Definitions of General Tread Pattern Features
FIG. 2 Uniform or Regular Wear
5.1 tread band, n— an annular volume of rubber that
encompasses the outer pavement contacting periphery of a tire;
4. Tire Inspection
the width is normally much greater than the thickness, and both
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. A movable secondary source of illumination with
6. Definitions of Subclassifications of Basic Tread Pattern
a light path tangential to the tread surface is often useful for
Features
viewing subtle wear features.
4.2.1 Observe the entire tread pattern of the tire and record 6.1 Grooves are major features that may be characterized as
the treadwear features of the tire according to the wear follows:
nomenclature system as given in Sections 7 and 8. 6.1.1 longitudinal groove, n—an endless groove that has its
4.3 There are two options for recording the observed tread major (long) dimension substantially paral
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