ASTM F1650-98(2014)
(Practice)Standard Practice for Evaluating Tire Traction Performance Data Under Varying Test Conditions
Standard Practice for Evaluating Tire Traction Performance Data Under Varying Test Conditions
ABSTRACT
This practice covers the required correction procedures for examining sequential control tire data for any systematic or bias (not random) variation due to changing test conditions that may influence absolute and also comparative performance of candidate tires, as they are tested over any short or extended time period. The procedures provided here may be used for any repetitive tire traction testing in any environment (for example, dry, wet, snow, ice) where test conditions are subject to change. This practice does not address the issue of rejecting outlier data points or test values that might occur among a set of otherwise acceptable data values obtained under identical test conditions in a short time period. Method A uses the initial operational conditions defined by the first control traction test as a reference point. The calculations correct all traction test performance parameters (for example, traction coefficients) to the initial level or condition of the pavement or other testing conditions, or both. With this method, corrections may be made after only a few candidate and control sets have been evaluated. Method B uses essentially the midpoint of any evaluation program, with the grand average traction test value as a reference point. This grand average value is obtained with higher precision than the initial control traction test average of Method A because it contains more values. However, Method B corrections cannot be made until the grand average value is established, which is normally at the end of any program.
SCOPE
1.1 This practice covers the required procedures for examining sequential control tire data for any variation due to changing test conditions. Such variations may influence absolute and also comparative performance of candidate tires, as they are tested over any short or extended time period. The variations addressed in this practice are systematic or bias variations and not random variations. See Appendix X1 for additional details.
1.1.1 Two types of variation may occur: time or test sequence “trend variations,” either linear or curvilinear, and the less common transient or abrupt shift variations. If any observed variations are declared to be statistically significant, the calculation procedures are given to correct for the influence of these variations. This approach is addressed in Method A.
1.2 In some testing programs, a policy is adopted to correct all candidate traction test data values without the application of a statistical routine to determine if a significant trend or shift is observed. This option is part of this practice and is addressed in Method B.
1.3 The issue of rejecting outlier data points or test values that might occur among a set of otherwise acceptable data values obtained under identical test conditions in a short time period is not part of this practice. Specific test method or other outlier rejection standards that address this issue may be used on the individual data sets prior to applying this practice and its procedures.
1.4 Although this practice applies to various types of tire traction testing (for example, dry, wet, snow, ice), the procedures as given in this practice may be used for any repetitive tire testing in an environment where test conditions are subject to change.
1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
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Designation: F1650 − 98(Reapproved 2014)
Standard Practice for
Evaluating Tire Traction Performance Data Under Varying
Test Conditions
This standard is issued under the fixed designation F1650; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
INTRODUCTION
Tiretractiontestingprogramsatprovinggroundsorotherexteriortestsitesareoftenextendedover
a period of days or weeks. During this time period test conditions may change due to a number of
varying factors, for example, temperature, rain or snow fall, surface texture, water depth, and wind
velocity and direction. If tire performance comparisons are to be made over any part of the test
program(ortheentireprogram)wherethesetestconditionvariationsareknownorsuspectedtoaffect
performance, the potential influence of these variations must be considered in any final evaluation of
traction performance.
1. Scope outlier rejection standards that address this issue may be used
ontheindividualdatasetspriortoapplyingthispracticeandits
1.1 This practice covers the required procedures for exam-
procedures.
ining sequential control tire data for any variation due to
changing test conditions. Such variations may influence abso- 1.4 Although this practice applies to various types of tire
lute and also comparative performance of candidate tires, as traction testing (for example, dry, wet, snow, ice), the proce-
they are tested over any short or extended time period. The dures as given in this practice may be used for any repetitive
variations addressed in this practice are systematic or bias tire testing in an environment where test conditions are subject
variations and not random variations. See Appendix X1 for to change.
additional details.
1.5 This standard does not purport to address all of the
1.1.1 Two types of variation may occur: time or test
safety concerns, if any, associated with its use. It is the
sequence“trendvariations,”eitherlinearorcurvilinear,andthe
responsibility of the user of this standard to establish appro-
less common transient or abrupt shift variations. If any
priate safety and health practices and determine the applica-
observed variations are declared to be statistically significant,
bility of regulatory limitations prior to use.
thecalculationproceduresaregiventocorrectfortheinfluence
of these variations. This approach is addressed in Method A. 2. Referenced Documents
1.2 In some testing programs, a policy is adopted to correct 2.1 ASTM Standards:
allcandidatetractiontestdatavalueswithouttheapplicationof E501 Specification for Rib Tire for Pavement Skid-
astatisticalroutinetodetermineifasignificanttrendorshiftis Resistance Tests
observed. This option is part of this practice and is addressed E524Specification for Smooth Tire for Pavement Skid-
in Method B. Resistance Tests
E826Practice for Testing Homogeneity of a Metal Lot or
1.3 The issue of rejecting outlier data points or test values
Batch in Solid Form by Spark Atomic Emission Spec-
that might occur among a set of otherwise acceptable data
trometry
values obtained under identical test conditions in a short time
E1136Specification for P195/75R14 Radial Standard Refer-
period is not part of this practice. Specific test method or other
ence Test Tire
This practice is under the jurisdiction ofASTM Committee F09 on Tires and is
the direct responsibility of Subcommittee F09.20 on Vehicular Testing. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved Jan. 1, 2014. Published February 2014. Originally contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
approved in 1995. Last previous edition approved in 2005 as F1650–98 (2005). Standards volume information, refer to the standard’s Document Summary page on
DOI: 10.1520/F1650-98R14. the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
F1650 − 98 (2014)
F538Terminology Relating to the Characteristics and Per- may occur. The procedures as described in this practice are
formance of Tires therefore needed to correct for these unavoidable testing
complications.
3. Terminology
5. Summary of Practice
3.1 Descriptions of Terms Specific to This Standard—
Descriptionsoftermsparticulartothispracticearelistedeither
5.1 This practice specifies certain test plans for testing
as principal terms or under principal terms as derived terms.
control tires. Testing begins with an initial test of the control
3.2 Discussion: tireortireset.Anumberofcandidatetiretractiontestsarethen
conducted followed by a repeat test of the control tire traction
3.2.1 The terminology in this section is currently under
review by Subcommittee F09.94 on Terminology. This termi- test. Additional candidate traction tests are conducted prior to
nologyissubjecttochangeandshouldbeconsideredtentative. the next control tire traction test. This sequential procedure is
repeated for the entire evaluation program.
3.2.2 candidate tire (set), n—a test tire (or test tire set) that
is part of an evaluation program; each candidate tire (set)
5.2 Using control tire average measured performance
usually has certain unique design or other features that distin-
parameters, the performance parameters of the candidate tires
guish it from other candidate tires in the program.
(sets) are corrected for any changes in test conditions. Two
3.2.3 control tire (set), n—a reference tire (or reference set)
correction procedures are described (MethodAand Method B)
repeatedly tested in a specified sequence throughout an evalu-
that use different reference points for data correction and as
ation program, that is used for data adjustment or statistical
such give different values for the corrected actual or absolute
procedures, or both, to offset or reduce testing variation and
traction parameters. However, both test methods give the same
improve the accuracy of candidate tire (set) evaluation or
relativeratingsortractionperformanceindexes.SeeSection10
detect test equipment variation, or both.
formoredetails.Thetwotestmethodsaresummarizedinmore
3.2.4 reference tire (set), n—a special test tire (test tire set) detail in Section 6 and Section 9. Both MethodsAand B have
that is used as a benchmark in an evaluation program; these
advantages and disadvantages.
tires usually have carefully controlled design features to
5.2.1 Method A uses the initial operational conditions de-
minimize variation.
fined by the first control traction test as a reference point. The
3.2.5 standard reference test tire, SRTT, n—atirethatmeets calculations correct all traction test performance parameters
the requirements of Specification E1136, commonly used as a
(for example, traction coefficients) to the initial level or
control tire or surface monitoring tire. condition of the pavement or other testing conditions, or both.
With this test method, corrections may be made after only a
3.2.6 surface monitoring tire (set), n— a reference tire (or
few candidate and control sets have been evaluated.
reference set), used to evaluate changes in the test surface over
a selected time period. 5.2.2 Method B uses essentially the midpoint of any evalu-
ation program, with the grand average traction test value as a
3.2.7 test, n—a technical procedure performed on an object
reference point. This grand average value is obtained with
(or set of objects) using specified equipment, that produces
higher precision than the initial control traction test average of
data; the data are used to evaluate or model selected properties
MethodA, since it contains more values. However, Method B
or characteristics of the object (or set of objects).
corrections cannot be made until the grand average value is
3.2.8 test run, n—in tire testing, a single pass (over a test
established, which is normally at the end of any program.
surface) or sequence of data acquisition, or both, in the act of
testing a tire or tire set under selected test conditions. 5.3 Annex A1 provides illustrations of several types of
typical variation patterns for control tire data. It additionally
3.2.9 test tire, n—a tire used in a test.
provides an example of the Method A correction calculations
3.2.10 test tire set, n—one or more tires, as required by the
required to evaluate a set of candidate test tires. Method B
test equipment or procedure, to perform a test, producing a
corrections follow the same general approach as illustrated in
single set of results; these tires are usually nominally identical.
Annex A1, with C used in place of C1.
avg
3.2.11 traction test, n— in tire testing, a series of n test runs
5.4 Annex A2 provides a recommended technique for
at a selected operational condition; a traction test is character-
weighting the correction of the two or three candidate values
ized by an average value for the measured performance
(for example, T1, T2, T3) between each pair of control values.
parameter.
This gives a slightly improved correction that may be impor-
tant in certain testing operations.
4. Significance and Use
5.5 Appendix X1 provides a statistical model for the trac-
4.1 Tire testing is conducted to make technical decisions on
tion measurement process. This may help the user of this
variousperformancecharacteristicsoftires,andgoodtechnical
practice to sort out the differences between fixed or bias
decisions require high quality test data. High quality test data
components of variation and random components of variation.
are obtained with carefully designed and executed tests.
AppendixX1givesarationalefortheproceduresasoutlinedin
However, even with the highest quality testing programs,
unavoidabletimeortestsequencetrendsorotherperturbations this practice.
F1650 − 98 (2014)
5.6 AnnexA2 contains some background and details on the tires constitute 67% of the tires tested, and Plan B, in which
propagation of error or test variation that occurs when correc- candidate tires constitute 75% of the tires tested.
tions are applied to the measured traction performance param-
7.4 Number of Test Runs at Each Speed or Operational
eters and when traction performance indexes are calculated.
Condition—The number of test runs or replicates, n, for each
speed or other selected operational condition for each candi-
METHOD A—DATA CORRECTIONS BASED ON
date tire set and each control set, except the first set, shall be
INITIAL CONTROL TRACTION TEST
selected. The number of test runs depends on the test method.
Good testing procedure calls for as many test runs as possible.
6. Summary of Method A
If direction of test is important on any test surface, one half of
6.1 This method corrects the data obtained throughout the
the test runs shall be in each direction.
evaluation program to the initial conditions (test surface or
7.4.1 Number of Test Runs: Initial Control Set—The initial
other, or both)“ reference point” at the beginning of the
test for the control, indicated by C1, is a key value used for
program.The correction procedure (and calculation algorithm)
correction of candidate set performance parameter values as
for time trend variations is mathematically equivalent to that
testing proceeds. Therefore, the average performance param-
described in Practice E826. The procedure used for abrupt or
etersforC1mustbeevaluatedwithahighdegreeofconfidence
step changes is provisional and is subject to change as
and the recommended number of test runs for C1 should be at
experience is gained. In this method the initial traction test
least two times the number of test runs selected in 7.4.
value for the control tire is a key data point. This method also
7.4.2 More than One Control Tire—Insometypesoftesting,
allows for decisions on the need for any correction, based on a
the control tire is damaged or changed by the testing to the
statistical analysis of the control tire data.
extent that it ceases to function as a stable control. In such
situations it is necessary to use more than one control tire
7. Procedure
throughoutanyevaluationprogram.Insuchcasesacontroltire
7.1 Thetestprocedureisgivenintermsoftestingtiresetsof
indicationschemesuchasC1-1,C1-2,C1-3,C2-4,C2-5,C2-6,
four tires, that is, one tire on each of four vehicle positions. If
C3-1, etc., is suggested. In this scheme, C1-1=control tire 1,
only one tire is to be tested (trailer or other dynamometer
sequence use 1; C1-2=control tire 1, sequence use 2; .,
vehicle testing), follow the procedure as outlined with the
C2-4=control tire 2, sequence use 4, etc.
understanding that the one tire replaces the tire set.
7.5 Table of Results—Prepare a table of test results and
7.2 Assemble all the tire sets to be tested in any evaluation
record all data with columns for:
program or for daily testing. Select the test speeds to be used
7.5.1 Test sequence number, a sequential indication from 1
and other operational test conditions as well as the order in
to m, of all the tests for any program of evaluation,
which the candidate tire sets are to be tested.
7.5.2 Tire set identification,
7.2.1 For any selected order, a test plan is established with
7.5.3 Speed or other selected operational test condition(s),
referencetire(s)designatedasacontroltiresettestedatregular
and
intervals among the selected candidate sets. Select the number
7.5.4 Average value (for n test runs) for the measured
oftestrunsorreplicatesforbothcontrolandcandidatetiresets.
parameter for that operational condition.
Acompletetestforatiresetisdefinedasthetotalof ptraction
7.6 Both control and candidate set data shall be included in
tests, one at each selected operational test condition, with n
the table in the order as tested. If deemed important, a separate
replicate test runs for each operational condition (for example,
table of ambient temperature, wind direction, wind velocity, or
speed and surface type).
other weather information also shall be prepared on a selected
7.2.2 Tests with a surface monitoring tire may also be
time (hourly) basis.
conducted on a regular basis in addition to the control tire.
7.3 Test Sequence—The control tires may be standard tires
8. Calculations for Corrected Traction Performance Data
as specified in Specifications E501, E524, and E1136, or a tire
8.1 Preliminary Control Set Data Review—The decision to
set similar in design and performance level to the candidate
correct data, for any part of the test program where candidate
sets. Conduct a complete test for the control sets in relation to
set comparisons are to be made, is based on the time or test
the
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