ASTM F408-21

Standard Test Method for Tires for Wet Traction in Straight-Ahead Braking, Using a Towed Trailer

SIGNIFICANCE AND USE
5.1 The measured values are traction properties of tires obtained with the towed trailer described here on a given road surface, under given environmental conditions (ambient and road surface temperature, humidity, wind speed and direction, purity and film depth of water used to wet the road surface). They are carried out in accordance with the stated test procedures and reflect the performance of the total tire-vehicle environmental system. A change in any of these factors may change the measurements on a subsequent run of the test.  
5.2 These test methods are suitable for research and development purposes, where tires are compared during a single series of tests. They may not be suitable for regulatory statutes or specification acceptance, because the values obtained may not necessarily agree or correlate either in rank order or absolute traction performance level with those obtained on other road surfaces (or the same surface after additional wear), under other environmental conditions, or other towed trailers, or other test devices, or with results obtained with other test procedures.
SCOPE
1.1 This test method covers the measurement of braking traction of tires designed for passenger cars or light trucks. Such braking traction measurements are applicable to conditions wherein the vehicle is traveling straight ahead on a wet, paved surface.  
1.2 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.  
1.3 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, health, and environmental practices and determine the applicability of regulatory limitations prior to use.  
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.

General Information

• Status: Published
• Publication Date: 31-Aug-2021
• ICS: 83.160.10 - Road vehicle tyres
• Technical Committee: F09 - Tires
• Drafting Committee: F09.20 - Vehicular Testing

Standards Content (Sample)

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.
Designation: F408 − 21
Standard Test Method for
Tires for Wet Traction in Straight-Ahead Braking, Using a
1
Towed Trailer
ThisstandardisissuedunderthefixeddesignationF408;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginal
adoptionor,inthecaseofrevision,theyearoflastrevision.Anumberinparenthesesindicatestheyearoflastreapproval.Asuperscript
epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope F538Terminology Relating to Characteristics and Perfor-
mance of Tires
1.1 This test method covers the measurement of braking
F1650Practice for Evaluating Tire Traction Performance
traction of tires designed for passenger cars or light trucks.
Data Under Varying Test Conditions
Such braking traction measurements are applicable to condi-
tions wherein the vehicle is traveling straight ahead on a wet,
3. Terminology
paved surface.
3.1 Definitions:
1.2 The values stated in SI units are to be regarded as the
3.1.1 braking force, [F], n—of a tire, the negative longitu-
standard. The values given in parentheses are for information
dinal force resulting from braking torque application. F538
only.
3.1.2 braking force coeffıcient, n—of a tire, the ratio of
1.3 This standard does not purport to address all of the
braking force to normal force. F538
safety concerns, if any, associated with its use. It is the
3.1.3 braking force coeffıcient, peak, n—of a tire, the maxi-
responsibility of the user of this standard to establish appro-
mum value of tire braking force coefficient that occurs prior to
priate safety, health, and environmental practices and deter-
wheel lockup as the braking torque is progressively increased.
mine the applicability of regulatory limitations prior to use.
F538
1.4 This international standard was developed in accor-
dance with internationally recognized principles on standard-
3.1.4 braking force coeffıcient, slide, n—of a tire, the value
ization established in the Decision on Principles for the
of braking force coefficient obtained on a locked wheel. F538
Development of International Standards, Guides and Recom- 2 2
3.1.5 braking torque, [ML /T ], n—of a vehicle, the
mendations issued by the World Trade Organization Technical
negative wheel torque. F538
Barriers to Trade (TBT) Committee.
3.1.6 lockup, n—of a wheel, the condition of a wheel in
which its rotational velocity about the wheel spin axis is zero
2. Referenced Documents
and it is prevented from rotating in the presence of applied
2
2.1 ASTM Standards:
wheel torque. F538
E274Test Method for Skid Resistance of Paved Surfaces
3.1.7 longitudinal force, [F], n—of a tire, the component of
Using a Full-Scale Tire
the tire force vector in the X' direction. F538
E1337Test Method for Determining Longitudinal Peak
Braking Coefficient (PBC) of Paved Surfaces Using Stan-
3.1.8 normal force, [F], n—of a tire,thecomponentofatire
dard Reference Test Tire
force vector in the Z' direction. F538
F377PracticeforCalibrationofBraking/TractiveMeasuring
3.1.9 skid number (SN), n—slide braking force coefficient
Devices for Testing Tires
multiplied by 100. F538
F457Test Method for Speed and Distance Calibration of
3.1.10 test run, n—in tire testing, a single pass over a given
Fifth Wheel Equipped With Either Analog or Digital
testsurface,ortheacquisitionofasequenceofdata,orboth,in
Instrumentation
theactoftestingatireortiresetunderselectedtestconditions.
F538
1
This test method is under the jurisdiction of ASTM Committee F09 on Tires
3.1.11 tire axis system, n—the origin of the tire-axis system
and is the direct responsibility of Subcommittee F09.20 on Vehicular Testing.
is the center of the tire contact where the X'-axis is the
Current edition approved Sept. 1, 2021. Published September 2021. Originally
intersection of the wheel plane and the road plane with a
approved in 1975. Last previous edition approved in 2015 as F408–99 (2015).
DOI: 10.1520/F0408-21.
positive direction forward, the Z'-axis is perpendicular to the
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
road plane with a positive direction downward, and theY'-axis
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
isintheroadplane,itsdirectionbeingchosentomaketheaxis
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. system orthogonal and right-hand. (See Fig. 1.) F538
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
1

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F408 − 21
under other environmental conditions, or other towed trailers,
or other test devices, or with resul
...

This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: F408 − 99 (Reapproved 2015) F408 − 21
Standard Test Method for
Tires for Wet Traction in Straight-Ahead Braking, Using a
1
Towed Trailer
This standard is issued under the fixed designation F408; 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 test method covers the measurement of braking traction of tires designed for passenger cars or light trucks. Such braking
traction measurements are applicable to conditions wherein the vehicle is traveling straight ahead on a wet, paved surface.
1.2 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.
1.3 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 safety, health, and healthenvironmental practices and determine the
applicability of regulatory limitations prior to use.
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. Referenced Documents
2
2.1 ASTM Standards:
E274 Test Method for Skid Resistance of Paved Surfaces Using a Full-Scale Tire
E1337 Test Method for Determining Longitudinal Peak Braking Coefficient (PBC) of Paved Surfaces Using Standard Reference
Test Tire
F377 Practice for Calibration of Braking/Tractive Measuring Devices for Testing Tires
F457 Test Method for Speed and Distance Calibration of Fifth Wheel Equipped With Either Analog or Digital Instrumentation
F538 Terminology Relating to Characteristics and Performance of Tires
F1650 Practice for Evaluating Tire Traction Performance Data Under Varying Test Conditions
3. Terminology
3.1 Definitions:
3.1.1 braking force, [F], n—of a tire, the negative longitudinal force resulting from braking torque application. F538
3.1.2 braking force coeffıcient, n—of a tire, the ratio of braking force to normal force. F538
3.1.3 braking force coeffıcient, peak, n—of a tire, the maximum value of tire braking force coefficient that occurs prior to wheel
lockup as the braking torque is progressively increased. F538
1
This test method is under the jurisdiction of ASTM Committee F09 on Tires and is the direct responsibility of Subcommittee F09.20 on Vehicular Testing.
Current edition approved May 1, 2015Sept. 1, 2021. Published June 2015September 2021. Originally approved in 1975. Last previous edition approved in 20082015 as
F408 – 99 (2008).(2015). DOI: 10.1520/F0408-99R15.10.1520/F0408-21.
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
1

---------------------- Page: 1 ----------------------
F408 − 21
3.1.4 braking force coeffıcient, slide, n—of a tire, the value of braking force coefficient obtained on a locked wheel. F538
2 2
3.1.5 braking torque, [ML /T ], n—of a vehicle, the negative wheel torque. F538
3.1.6 lockup, n—of a wheel, the condition of a wheel in which its rotational velocity about the wheel spin axis is zero and it is
prevented from rotating in the presence of applied wheel torque. F538
3.1.7 longitudinal force, [F], n—of a tire, the component of the tire force vector in the X' direction. F538
3.1.8 normal force, [F], n—of a tire, the component of a tire force vector in the Z' direction. F538
3.1.9 skid number (SN), n—slide braking force coefficient multiplied by 100. F538
3.1.10 test run, n—in tire testing, a single pass of a loaded tire over a given test surface.surface, or the acquisition of a sequence
of data, or both, in the act of testing a tire or tire set under selected test conditions. F538
3.1.11 tire axis system, n—the origin of the tire-axis system is the center of the tire contact where the X'-axis is the intersection
of the wheel plane and the road plane with a positive direction forward, t
...