ASTM F1805-20

Standard Test Method for Single Wheel Driving Traction in a Straight Line on Snow- and Ice-Covered Surfaces

SIGNIFICANCE AND USE
5.1 This test method describes a technique for assessing the performance characteristics of tires in a winter environment on snow and ice surfaces. When snow is referred to hereafter, ice is implied as appropriate.  
5.2 The measured values quantify the dynamic longitudinal traction properties of tires under driving torque. Dynamic traction properties are obtained on snow surfaces prepared in accordance with the stated test procedures and attempts to quantify the tires' performance when integrated into a vehicle-environmental system. Changing any one of these environmental factors will change the measurements obtained on a subsequent test run.  
5.3 This test method addresses longitudinal driving traction properties only on snow and ice surfaces. Refer to Test Methods F1572 for test methods for braking and lateral traction properties on snow or ice, or both.
SCOPE
1.1 This test method covers a procedure for measuring the driving traction of passenger car and light truck tires while traveling in a straight line on snow- or ice-covered surfaces.  
1.2 This test method utilizes a dedicated, instrumented, four-wheel rear-wheel drive test vehicle with a specially instrumented drive axle to measure fore-aft and vertical forces acting on a single driven test tire.  
1.3 This test method is 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 under other environmental conditions on other surfaces or the same surface after additional use.  
1.4 The values stated in SI units are to be regarded as the standard. Ordinarily, N and kN should be used as units of force. This standard may utilize kgf as a unit of force in order to accommodate the use of load and pressure tables, as found in other standards both domestic and global that are commonly used with this standard. The values given in parentheses are for information only.  
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, health, and environmental practices and determine the applicability of regulatory limitations prior to use.  
1.6 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: 30-Apr-2020
• ICS: 83.160.10 - Road vehicle tyres
• Technical Committee: F09 - Tires
• Drafting Committee: F09.20 - Vehicular Testing

Relations

• Refers: ASTM E1136-19 - Standard Specification for P195/75R14 Radial Standard Reference Test Tire
• Effective Date: 01-Oct-2019
• Refers: ASTM F2493-18 - Standard Specification for P225/60R16 97S Radial Standard Reference Test Tire
• Effective Date: 01-Jan-2018
• Refers: ASTM E1136-17 - Standard Specification for P195/75R14 Radial Standard Reference Test Tire
• Effective Date: 01-Oct-2017
• Refers: ASTM E1136-14 - Standard Specification for P195/75R14 Radial Standard Reference Test Tire
• Effective Date: 15-Aug-2014
• Refers: ASTM F2493-14 - Standard Specification for P225/60R16 97S Radial Standard Reference Test Tire
• Effective Date: 01-Jun-2014
• Refers: ASTM F1650-98(2014) - Standard Practice for Evaluating Tire Traction Performance Data Under Varying Test Conditions
• Effective Date: 01-Jan-2014
• Refers: ASTM F377-03(2009) - Standard Practice for Calibration of Braking/Tractive Measuring Devices for Testing Tires
• Effective Date: 01-Nov-2009
• Refers: ASTM F538-09 - Standard Terminology Relating to the Characteristics and Performance of Tires
• Effective Date: 15-Jun-2009
• Refers: ASTM F1046-01(2008) - Standard Guide for Preparing Artificially Worn Passenger and Light Truck Tires for Testing
• Effective Date: 01-Oct-2008
• Refers: ASTM F1572-08 - Standard Test Methods for Tire Performance Testing on Snow and Ice Surfaces
• Effective Date: 01-Oct-2008
• Refers: ASTM F2493-08 - Standard Specification for P225/60R16 97S Radial Standard Reference Test Tire
• Effective Date: 01-May-2008
• Refers: ASTM F2493-06 - Standard Specification for P225/60R16 97S Radial Standard Reference Test Tire
• Effective Date: 01-Dec-2006
• Refers: ASTM F1572-99(2005) - Standard Test Methods for Tire Performance Testing on Snow and Ice Surfaces
• Effective Date: 01-Nov-2005
• Refers: ASTM F1650-98(2005) - Standard Practice for Evaluating Tire Traction Performance Data Under Varying Test Conditions
• Effective Date: 01-Nov-2005
• Refers: ASTM F538-03 - Standard Terminology Relating to the Characteristics and Performance of Tires
• Effective Date: 01-Dec-2003

Overview

ASTM F1805-20: Standard Test Method for Single Wheel Driving Traction in a Straight Line on Snow- and Ice-Covered Surfaces is an internationally recognized procedure developed by ASTM International. This standard focuses exclusively on measuring and comparing the straight-line driving traction performance of passenger car and light truck tires under winter conditions, specifically on snow and ice surfaces.

By establishing a repeatable, well-instrumented test methodology, ASTM F1805-20 provides valuable data for tire development, performance benchmarking, and comparative research by quantifying the dynamic longitudinal traction properties of tires as part of the vehicle-environment system.

Key Topics

• Purpose: Assesses tire performance in winter environments, specifically longitudinal driving traction on snow and ice, using a controlled test vehicle and test wheel setup.
• Scope: Covers procedures for measuring the straight-line driving traction of individual tires fitted on specially equipped, instrumented test vehicles.
• Test Vehicle: Utilizes a four-wheel, rear-wheel drive passenger car or light truck fitted with a dedicated, instrumented drive axle for accurate force measurement.
• Environmental Factors: Recognizes the critical influence of snow type, temperature, surface grooming, tire pressure, tire wear, and loading conditions on traction measurements.
• Measurement: Focuses on fore-aft (longitudinal) and vertical force measurement, with calculations based on driving coefficient (ratio of driving force to normal force).
• Limitations: Results are intended for comparative purposes within a controlled testing program and are not suitable for regulatory compliance or specification approval. Measurements are environment- and surface-specific.
• Units: Relies predominantly on SI units (N and kN), with allowances for kgf where compatibility with other standards is needed.

Applications

• Tire Research & Development: Enables manufacturers and researchers to compare tire designs and compounds for performance on snow and ice, supporting optimization of tread patterns and materials for improved winter safety.
• Winter Tire Benchmarking: Provides a scientific basis for evaluating and benchmarking tires marketed under severe snow service claims, including those needing to meet the "Three-Peak Mountain Snowflake" (3PMSF) symbol requirements.
• Comparative Testing: Essential for internal product testing, competitor analysis, and tire selection for fleet managers and automotive OEMs targeting markets with winter driving conditions.
• Surface Monitoring: Assists test engineers in monitoring surface conditions during testing using standardized reference test tires, ensuring consistency and reliability of results.
• Industry Standards Alignment: Supports harmonization with related global standards and tire industry practices, including those published by ETRTO, JATMA, and the Tire & Rim Association.

Related Standards

• ASTM E1136: Specification for P195/75R14 Radial Standard Reference Test Tire, commonly used as a control tire in this method.
• ASTM F2493: Specification for P225/60R16 97S Radial Standard Reference Test Tire, validated as an acceptable future control tire.
• ASTM F1572: Test Methods for Tire Performance Testing on Snow and Ice Surfaces (for braking and lateral traction assessments).
• ASTM F377: Practice for Calibration of Braking/Tractive Measuring Devices for Testing Tires.
• ASTM F1650: Practice for Evaluating Tire Traction Performance Data Under Varying Test Conditions.
• Tire Industry Manuals: Refer to the European Tyre and Rim Technical Organisation (ETRTO) Standards Manual, Japan Automobile Tyre Manufacturers Association (JATMA) Yearbook, and the Tire & Rim Association's Year Book for rim and load specifications.

Keywords: tire traction, snow and ice testing, single wheel vehicle, winter tire performance, driving traction, ASTM F1805, standard reference test tire, snow tire benchmarking, winter testing standards

ASTM F1805-20 is foundational for anyone involved in tire testing, winter tire development, and traction performance evaluation, ensuring a consistent, reliable approach for measuring tire traction under winter driving conditions.

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: F1805 − 20
Standard Test Method for
Single Wheel Driving Traction in a Straight Line on Snow-
and Ice-Covered Surfaces
This standard is issued under the fixed designation F1805; 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.
1. Scope 2. Referenced Documents
2.1 ASTM Standards:
1.1 This test method covers a procedure for measuring the
E1136Specification for P195/75R14 Radial Standard Refer-
driving traction of passenger car and light truck tires while
ence Test Tire
traveling in a straight line on snow- or ice-covered surfaces.
F377PracticeforCalibrationofBraking/TractiveMeasuring
1.2 This test method utilizes a dedicated, instrumented,
Devices for Testing Tires
four-wheel rear-wheel drive test vehicle with a specially
F538Terminology Relating to the Characteristics and Per-
instrumented drive axle to measure fore-aft and vertical forces
formance of Tires
acting on a single driven test tire.
F1046Guide for Preparing Artificially Worn Passenger and
Light Truck Tires for Testing
1.3 This test method is suitable for research and develop-
F1572Test Methods for Tire Performance Testing on Snow
ment purposes where tires are compared during a single series
and Ice Surfaces
of tests. They may not be suitable for regulatory statutes or
specification acceptance because the values obtained may not F1650Practice for Evaluating Tire Traction Performance
Data Under Varying Test Conditions
necessarily agree or correlate either in rank order or absolute
traction performance level with those obtained under other F2493Specification for P225/60R16 97S Radial Standard
Reference Test Tire
environmentalconditionsonothersurfacesorthesamesurface
after additional use. 2.2 Other Standards:
The European Tyre and Rim Technical Organisation Stan-
1.4 The values stated in SI units are to be regarded as the
dards Manual
standard.Ordinarily,NandkNshouldbeusedasunitsofforce.
TheJapanAutomobileTyreManufacturersAssociation,Inc.
This standard may utilize kgf as a unit of force in order to
Yearbook
accommodate the use of load and pressure tables, as found in
The Tire & Rim Association, Inc. Year Book
other standards both domestic and global that are commonly
Tire Information Service Bulletin, Vol. 37/No. 6U.S. Tire
usedwiththisstandard.Thevaluesgiveninparenthesesarefor
Manufacturers Association (USTMA) Definition for Pas-
information only.
senger and Light Truck Tires for Use in Severe Snow
1.5 This standard does not purport to address all of the
Conditions
safety concerns, if any, associated with its use. It is the
3. Terminology
responsibility of the user of this standard to establish appro-
priate safety, health, and environmental practices and deter- 3.1 Definitions:
mine the applicability of regulatory limitations prior to use.
3.1.1 candidate tire, n—a test tire that is part of a test
program. F538
1.6 This international standard was developed in accor-
dance with internationally recognized principles on standard-
ization established in the Decision on Principles for the
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
Development of International Standards, Guides and Recom-
Standards volume information, refer to the standard’s Document Summary page on
mendations issued by the World Trade Organization Technical
the ASTM website.
Barriers to Trade (TBT) Committee.
AvailablefromTheEuropeanTyreandRimTechnicalOrganisation,78/80,rue
Defacqz B-1060, Brussels, Belgium.
Available from The Japan Automobile Tyre Manufacturers Association, Inc.,
No. 33 Mori Bldg. 8th Floor, 3-8-21 Toranomon, Minato-ku, Toyko, Japan 105-
This test method is under the jurisdiction of Committee F09 on Tires and is the 0001.
direct responsibility of Subcommittee F09.20 on Vehicular Testing. Available from The Tire & Rim Association, Inc., 175 Montrose West Ave.,
Current edition approved May 1, 2020. Published May 2020. Originally Suite 150, Copley, OH 44321.
approved in 1997. Last previous edition approved in 2018 as F1805–18. DOI: Available from the U.S. Tire ManufacturersAssociation, 1400 K Street, N.W.,
10.1520/F1805-20. Washington D.C. 20005, www.ustires.org/publications.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
F1805 − 20
3.1.1.1 Discussion—The term “candidate object” may be F2493 for future use as a primary reference tire for the Severe
used in the same sense as candidate tire. Snow Use Symbol (3 peak mountain snowflake). As of 2020
the Specification E1136 P195/75R14 92S Standard Reference
3.1.2 control tire, n—a reference tire used in a specified
Test Tire is expected to cease production. Upon that
manner throughout a test program. F538
occurrence,theSpecificationF2493P225/60R1697SStandard
3.1.2.1 Discussion—Acontroltiremaybeofeithertypeand
Reference Test Tire is an acceptable replacement for the
typicaltireusedisthereference(control)tireinPracticeF1650
Specification E1136 SRTT.
that provides algorithms for correcting (adjusting) test data for
3.1.17 surface monitoring tire, n—a reference tire used to
bias trend variations. (See Practice F1650. See also the
evaluatechangesinthetestsurfaceoveraselectedtimeperiod.
discussion in 3.1.16.)
F538
3.1.3 driving coeffıcient (nd), n—the ratio of the driving
force to a normal force. F538
3.1.18 test (or testing), n—a procedure performed on an
object (or set of nominally identical objects) using specified
3.1.4 driving force (F), n— of a tire, the positive longitudi-
equipment that produces data unique to the object (or set).
nalforceresultingfromtheapplicationofdrivingtorque. F538
F538
3.1.5 grooming, v—in tire testing,mechanicallyreworkinga
3.1.18.1 Discussion—Test data are used to evaluate or
snow test surface in order to obtain a surface with more
modelselectedpropertiesorcharacteristicsoftheobject(orset
consistent properties. F538
ofobjects).Thescopeoftestingdependsonthedecisionstobe
3.1.6 ice, dry, n—smooth ice without loose surface
madeforanyprogram,andsamplingandreplicationplans(see
materials. F538
definitions below) need to be specified for a complete program
3.1.7 longitudinal force (F), n— of a tire, the component of
description.
the tire force vector in the X' direction. F538
3.1.19 test matrix, n— in tire testing a group of candidate
3.1.8 longitudinal slip velocity (L/T), n— the effective
tires, usually with specified reference tires; all tests are
rolling radius multiplied by the difference between the spin
normally conducted in one testing program. F538
velocity (in rad/unit time) of a driven or braked tire and that of
3.1.20 test run, n—asinglepassofaloadedtireoveragiven
afreerollingtirewheneachistravelinginastraightline. F538
test surface. F538
3.1.9 maximum rated load, n—theloadcorrespondingtothe
3.1.21 test tire, n—a tire used in a test. F538
maximum tire load capacity at the rated inflation pressure in
accordance with the publications of tire and rim standards
3.1.22 test tire set, n—one or more test tires, as required by
current at the time of manufacture. F538
the test equipment or procedure, to perform a test, thereby
3.1.10 reference tire, n—a special tire included in a test producing a single test result. F538
program;thetestresultsforthistirehavesignificanceasabase
3.1.22.1 Discussion—The four nominally identical tires re-
value or internal benchmark. F538
quiredforvehiclestoppingdistancetestingconstituteatesttire
set. In the discussion below where the test tire is mentioned, it
3.1.11 snow, hard pack, n— in tire testing, packed base
without loose snow. F538 is assumed that the test tire set may be substituted for the test
tire, if a test tire set is required for the testing.
3.1.12 snow, medium pack, n— in tire testing, groomed
packed base with 2.5 to 5.0 cm (1 to 2 in.) loose snow. F538
3.1.23 traction test, n— in tire testing,aseriesof ntestruns
at a selected operational condition; a traction test is character-
3.1.13 snow, medium hard pack, n— in tire testing, packed
ized by an average value for the measured performance
base with some loose snow. F538
parameter. F538
3.1.14 snow, soft pack, n— in tire testing, freshly fallen or
deeplygroomedbasesnowwith5.0to7.5cm(2to3in.)loose 3.1.24 vertical load, n—the normal reaction of the tire on
snow. F538
the road which is equal to the negative of normal force. F538
3.1.15 spin velocity, n—the angular velocity of the wheel
4. Summary of Test Method
about its spin axis. F538
3.1.16 standard reference test tire (SRTT), n—a tire that is
4.1 These test methods describe the use of an instrumented
used as a control tire or surface monitoring tire (for example, vehicle with a single test wheel capable of measuring the tire
Specification E1136 and Specification F2493 tires). F538
performance properties under drive torque on snow and ice
surfaces when traveling in a straight line.
3.1.16.1 Discussion—While ASTM designates several tire
specifications as Standard Reference Test Tires, Test Method
4.2 Thetestisconductedbydrivingthetestvehicleoverthe
F1805 has historically used the Specification E1136 tire as its test surface. Driving torque is gradually increased to the test
primary reference tire and this specification is specifically
wheelwhilemaintainingthevehiclespeedbyapplyingbraking
identified as the control tire in the USTMA Tire Information torque to the non-test wheels of the vehicle. The driving
Service Bulletin Vol. 37/No. 6, which specifies requirements
traction coefficient is determined from the measured values of
for application of the Severe Snow Use Symbol (3 peak longitudinal and vertical forces over a specified slip or time
mountain snowflake).
range. The recommended vehicle test speed is 8.0 km/hr
3.1.16.2 Discussion—ASTM has validated Specification (5.0mph).
F1805 − 20
5. Significance and Use 7.6.1 The tire installed opposite the instrumented test wheel
shall have a sufficiently large traction coefficient to minimize
5.1 This test method describes a technique for assessing the
slipofthistireduringthetractiontest.Theoppositetireshould
performancecharacteristicsoftiresinawinterenvironmenton
have a coefficient at least 50% greater than the expected
snow and ice surfaces. When snow is referred to hereafter, ice
coefficient of the test tire. A tire chain may be utilized to
is implied as appropriate.
increase the traction of the opposite tire when testing on snow
5.2 The measured values quantify the dynamic longitudinal
surfaces.
traction properties of tires under driving torque. Dynamic
7.6.2 The opposite tire shall be selected to have an outside
traction properties are obtained on snow surfaces prepared in
diameterthatiswithin 62.5cm(61in.)ofthatofthetesttire.
accordance with the stated test procedures and attempts to
7.7 Asuitablerideheightadjustmentsystemontherearaxle
quantify the tires’ performance when integrated into a vehicle-
shall be provided to permit adjustment for each tire size and
environmentalsystem.Changinganyoneoftheseenvironmen-
load to minimize transducer crosstalk as established during
tal factors will change the measurements obtained on a
calibration.
subsequent test run.
7.8 Instrumentation—The test wheel position on the test
5.3 This test method addresses longitudinal driving traction
vehicle shall be equipped with a wheel rotational velocity
properties only on snow and ice surfaces. Refer to Test
measuring system and with transducers to measure the dy-
MethodsF1572fortestmethodsforbrakingandlateraltraction
namic longitudinal force and vertical load at the test wheel.
properties on snow or ice, or both.
7.8.1 General Requirements for Measurement System—The
6. Interferences instrumentation system shall conform to the following overall
requirements at ambient temperatures between –23 and 43°C
6.1 Factors that may affect tire snow performance and must
(–10 and 110°F):
be considered in the final analysis of data include:
7.8.1.1 Overall system accuracy, force—61.5%ofvertical
6.1.1 Snow temperature,
load or traction force from 450 N (100 lbf) to full scale.
6.1.2 Ambient temperature,
7.8.1.2 Overall system accuracy, speed—6 1.5% of speed
6.1.3 Mechanical breakdown of the agglomerated snow-
from 6.4 km/h (4.0 mph) to 48.0 km/h (30.0 mph).
flake into granular crystals,
7.8.1.3 Shunt Calibration—Allstrain-gagetransducersshall
6.1.4 Solar load,
be equipped with shunt calibration resistors that can be
6.1.5 Tire temperature,
connected before or after test runs.The calibration signal shall
6.1.6 Tire wear condition (preparation),
beintherangeoftheexpectedmeasurementforeachanalogue
6.1.7 Tire pressure,
channel.
6.1.8 Tire vertical load,
7.8.1.4 Ruggedness—The exposed portions of the system
6.1.9 Snow surface characteristics, and
shall tolerate 100% relative humidity (rain or spray) and all
6.1.10 Rim selection.
other adverse conditions such as dust, shock, and vibrations
7. Apparatus which may be encountered in regular operation.
7.8.2 Vehicle Speed—Vehicle forward speed (normally ob-
7.1 The test vehicle shall have the capability of maintaining
tained from a front non-driven wheel on the test vehicle) shall
the specified test speed 6 0.8 km/h (6 0.5 mph) during all
bemeasureddigitallywithanencoderoropticalsystemhaving
levels of driving torque application.
a minimum of 500 counts per revolution. Output shall be
7.2 The test vehicle shall be equipped with an automatic
directly visible to the driver and shall be simultaneously
throttleactuatortoallowthegradualincreaseofdrivingtorque
recorded.Itmaybenecessaryonaverylowcoefficientsurface,
at a predetermined (repeatable) rate.
thatis,ice,todisconnectanybrakingactiontothewheelbeing
7.3 The test vehicle shall be a rear drive, four wheel utilized for measuring vehicle speed. A separate fifth-wheel
passenger car or a light truck less than or equal to 44.5 kN system may be utilized to measure vehicle forward speed.
(10000 lbf) GVW. The range of test tires and load conditions 7.8.3 Test Wheel Speed—Test wheel speed shall be mea-
will determine the vehicle size and selection. Utilizing a front sured digitally with an encoder or optical system having a
wheel drive test vehicle is not addressed in this standard minimum of 1000 counts per wheel revolution. The output
although the basic procedures could be applied with appropri-
shall be recorded.
ate conditional modifications. 7.8.4 Vertical Load—The vertical load-measuring trans-
ducer shall measure the vertical load at the test wheel during
7.4 The test vehicle shall be instrumented to measure
drivingtorqueapplication.Thetransducerfullscalerangeshall
longitudinal and vertical forces at the tire and test surface
be in excess of the dynamic loading during a test. Data points
interface during the application of driving torque.
shall be evaluated to ensure dynamic loading is within the
7.5 The test vehicle shall have provisions to automatically
calibrated range of the transducer. The static load should be
and completely disengage the brake on the test wheel (if
less than 80 % of the calibrated range. The transducer design
installed) prior to throttle application. Complete disengage-
and location shall minimize inertial effects and vibration-
ment is necessary to eliminate all drag that might be caused by
induced mechanical resonance. The transducer shall have an
the brake assembly.
output directly proportional to the force with less than 1 %
7.6 Opposite Tire: hysteresis and less than 1 % nonlinearity at full scale. It shall
F1805 − 20
have less than 2 % cross-axis sensitivity at full scale. The 8.3 Calibrate the transducer for measuring vertical and
transducer shall be installed in such a manner as to experience horizontal forces on the test wheel with the reference load cell
less than 1° angular rotation with respect to its measuring axes in accordance with Practice F377.
at a maximum expected driving torque. The transducers 8.3.1 For longitudinal force calibration, place vehicle trans-
typically have a minimum full scale range of 0 to 8.9 kN mission in “park” position. Restrain the test vehicle using the
(2000lbf). vehicle brakes normally used while testing.
7.8.5 Driving Traction Forces—The driving traction force-
8.4 Calibrate the vehicle and test tire speed transducers and
measuring transducers shall measure longitudinal force gener-
any other instrumentation in accordance with the manufactur-
ated at the tire-road interface as a result of driving torque
ers’ specification.
application with a full scale range of at least 100 % of the
8.5 Calibrate temperature measuring devices (snow and
applied static vertical load. Otherwise, the transducers shall
ambient temperatures) in accordance with the manufacturer’s
have the same specifications as those described in 7.8.4.
recommendations.
7.8.6 Signal Conditioning and Recording System—All sig-
8.6 Calibrate pressure measuring devices in accordance
nal conditioning and recording equipment shall provide linear
with the manufacturer’s recommendations.
output with necessary gain and reading resolution to meet the
requirements of 7.8.1.Additionally, it shall have the following
9. Selection and Preparation of Test Tires
specifications:
7.8.6.1 Minimum Frequency Response—flat from dc to 18 9.1 Ensure all test tires are approximately the same age and
Hz, within 61%, stored essentially at the same conditions prior to testing unless
otherwise specified. When testing to the requirements of the
NOTE1—Basedonastudyofasampleacquisitionandforcetransducer
latest version of Tire Information Service Bulletin Vol. 37, the
system, a resonant frequency of 20 Hz was measured.
SRTTSpecificationE1136(orSpecificationF2493)controltire
7.8.6.2 Signal-to-Noise Ratio—at least 20/1,
shall be less than 2 years old based on the week/year
manufacture date molded into the tire sidewall.
7.8.6.3 Gain shall be sufficient to permit full-scale display
for full-scale input signal level,
9.2 Test tires shall have no evidence of force or run-out
7.8.6.4 Input impedance shall be at least ten times larger
grinding.
than the output impedance of the signal source,
9.3 New test tires shall be trimmed to remove all protuber-
7.8.6.5 The system must be insensitive to vibrations,
ances in the tread area caused by mold air vents or flashing at
acceleration, and changes in ambient temperature.The error in
mold junctions.
reading shall not exceed 1% full scale when subjected to
9.4 Any objects (for example, shipping labels) in the tread
vibration acceleration of 49.0 m/s (5 g’s) in the 0.5 to 40 Hz
area shall be removed prior to testing.
frequency range and operating temperature range from –23 to
43°C (–10 to 110°F),
9.5 Tires that have been buffed to simulate wear must be
prepared and run until all evidence of buffing is removed in
7.8.6.6 Thesystemshallnotbeaffectedbystoragetempera-
accordance with Guide F1046.
ture variations between –40 and 71°C (–40 and 160°F),
7.8.6.7 The individual data inputs shall have a sample rate
9.6 Mount the test tires on rims specified by the appropriate
of not less than 100 samples/s. For a given sample, vehicle
tireandrimstandardsorganization,usingconventionalmount-
speed, test wheel speed, vertical load, and driving traction
ing methods. Ensure proper bead seating by the use of a
force shall all be recorded within 0.0005 s,
suitablelubricant.Excessiveuseoflubricantshouldbeavoided
topreventslippingofthetireonthewheelrim.Ensuretiresare
7.8.7 Power Supply—The power supply for transducers and
mounted so the intended rotational direction of the tire corre-
recording system shall meet or exceed requirements specified
sponds with the test wheel position of the test vehicle. If
by transducer and recorder manufacturers.
rotation direction of the tire is not specified, the tire shall be
7.8.8 Temperature measurement devices for taking surface
mounted so during testing it rotates clockwise when viewed
and ambient temperatures shall have a resolution of 0.5°C
from the intended outboard sidewall of the tire.
(1°F) and an accuracy of 61°C (62°F).
9.7 Test tire balance is not necessary.
7.8.9 Pressuremeasurementdevicesforsettingtirepressure
shall have a resolution of 3.5 kPa ( ⁄2 psi) and an accuracy of
9.8 Newtesttirebreak-inisoptional,however,thedesignof
63.5 kPa (6 ⁄2 psi).
the test may necessitate on-the-road conditioning of up to
322km(200miles).Tirebreak-inmayimproverepeatabilityof
8. Calibration
results on ice surfaces.
8.1 All instrumentation shall be calibrated within six
9.9 Mounted test tires shall be placed near the test site in
months prior to testing.
suchalocationthattheyallhavethesametemperaturepriorto
testing. Test tires should be shielded from the sun to avoid
8.2 Calibrate the reference load cell by inputting known
excessive heating by solar radiation.
vertical and horizontal forces. The known forces must be
traceabletotheNationalInstituteofStandardsandTechnology 9.10 Test tires shall be checked and adjusted for specified
(NIST). pressure just prior to testing.
F1805 − 20
10. Preparation of Apparatus 11.2 Lift the rear axle so that the rear tires are off the
ground.
10.1 All transducers and instrumentation shall have been
calibrated in accordance with Section 8. 11.3 Install a control or candidate tire at the test wheel
position with the vehicle jacked up.
10.2 Turnonthetestvehicleinstrumentationandallowitto
warm up as required for stabilization. 11.4 Oppositethetestwheelpositioninstallatirethathasan
outside diameter within 62.5 cm (61 in.) of the test tire. A
10.3 Ensurethetestvehiclehassufficientfueltocompletea
chained tire is optional in snow.
test matrix.
11.5 Record basic test information and tire conditions.
10.4 Maneuver the test vehicle to the tire changing area.
Ambient and surface temperatures shall be updated with each
10.5 Position the temperature measurement devices.
control tire.
10.6 Allowsufficienttimetoensurethatthetemperaturesof
11.6 With the transmission in park or neutral, tare vertical
all equipment have stabilized.
load and tractive force by zeroing the signals.
10.7 Set the front speed reference tire or fifth wheel to the
11.7 Verify the vehicle and test wheel speeds are zero.
pressure utilized during the speed calibration 63.5 kPa
11.8 Lower the rear axle, placing the tires on the ground.
(60.5psi). Non-test rear tire pressures should be set as
appropriate. 11.9 Ballast the test tire for the desired load, 622 N
(65lbf), and set the tire to the specified test inflation pressure,
10.8 Perform a resistive shunt calibration on the force
63.5kPa (60.5 psi). One of the following three options shall
transducersonceperdayataminimum.Itisrecommendedthat
be selected for determining load and inflation pressure for
aresistiveshuntcalibrationcheckbeperformedatthestartand
testing.Theoptionselectedshallbenotedinthefinalreport.If
end of each testing day.
computedtestloadexceedsthetestequipmentcapabilities,test
11. Procedure inflation rated load and its corresponding pressure may be
reduced to the next lower load/pressure increment and a new
11.1 Course Surface—See Annex A1 – Annex A4 for
test load/pressure recomputed. See AnnexA5 for examples of
environmental and snow properties, surface characterization,
load and pressure determination for options 1 and 2. Table 1
course preparation, and course maintenance. When testing to
summarizes the various test load and pressure options.
the requirements of the Tire Information Service Bulletin Vol.
37/No. 6, a medium-packed snow surface shall be used. NOTE 2—A P195/75R14 SRTT (Specification E1136) control tire is
TABLE 1 Test Load and Test Pressure Options
F1805
F1805 Marked Sidewall F1805
Tire Type Test Pressure
Test Option max psi Test Load
psi
1 Passenger car tire Any 70 % of Maximum rated load 36
(TRA/ETRTO/JATMA) or 567 kgf (1250 lbf) max
Light Truck Any 70 % of Maximum rated load 51
(TRA/ETRTO/JATMA) or 567 kgf (1250 lbf) max
2 Pmetric LL,SL 35 74 % * table value 35
at test pressure
44 74 % * table value 35
at test pressure
51 74 % * table value 35
at test pressure
Pmetric XL 41 74 % * table value 41
at test pressure
50 74 % * table value 41
at test pressure
LT-metric 74 % * table value 50
at test pressure
Flotation-LT 74 % * table value 35
at test pressure
Eurometric C (Commercial LT) 74 % * table value 51
at test pressure
Eurometric SL 32 74 % * table value 32
at test pressure
36 74 % * table value 36
at test pressure
44 74 % * table value 36
at test pressure
51 74 % * table value 36
at test pressure
Eurometric XL 42 74 % * table value 42
at test pressure
51 74 % * table value 42
at test pressure
3 Any Any Any
F1805 − 20
tested at a load of 468 kgf (1031 lbf) and a pressure of 240 kPa (35 psi). NOTE 3—A single control or candidate tire may be used repeatedly as
AP225/60R16 SRTT (Specification F2493) control tire is tested at a load long as the tread surface maintains a “new” appearance.
of 531 kgf (1171 lbf) and a pressure of 240 kPa (35 psi).
11.17 Each candidate tire should be tested at least three
11.9.1 Option 1—The test load for passenger car tires shall
times, preferably on different days.
be the lower value of 70 % of the maximum rated load of the
11.18 Each new test tire shall be run on a surface as near as
tireor567kgf(1250lbf).Thetestloadforlighttrucktiresshall
possible to the previous pass. Care must be taken not to allow
be the lower value of 70 % of the maximum rated load of the
the test tire to drift into disturbed snow used during previous
tire or 567 kgf (1250 lbf).An inflation pressure of 250 kPa (36
test runs.
psi)shallbeusedforpassengertiresand350kPa(51psi)shall
11.19 Testing continues until the total test sequences or test
be used for light truck tires.
matrix is completed or the available test surface is exhausted.
11.9.2 Option 2—Thetestloadshallbeequalto74%ofthe
Regroomingthecoursewillnormallyallowtestingtocontinue.
rated load at the test inflation pressure as shown in the Tire &
Rim Association (TRA) Year Book, in the European Tyre and
12. Calculation
Rim Technical Organisation Manual (ETRTO), or in the Japan
Automobile Tyre Manufacturers Association Manual
12.1 For each test run of each control and candidate tire,
(JATMA). See Table 1. This option meets the requirement for read from accumulated data the values of longitudinal force
equivalent percentage loads as specified in the USTMA Tire
and vertical load corresponding to the values of longitudinal
Information Service Bulletin Vol. 37/No. 6. slip velocity within the range 1.6 and 24 km/h (1 and 15 mph)
11.9.3 Option 3—The test tire loads and inflation pressures or a range starting at 3.2 km/h (2 mph) and continuing for 1.5
shall be any other loads and pressures required to meet the s. Calculate the average force and load values over the
individual requirements of a specific test program. specified slip or time range. Calculate the average values of
driving coefficient as follows:
11.10 Adjust the vehicle ride height to the value established
F
during the calibration for minimum crosstalk taking into
u 5 (1)
W
account differences in tire dimensions.
11.11 Re-verify test load.Adjusting vehicle ride height may where:
change the test load. Several load/ride height adjustments may
u = average driving coefficient,
be necessary before meeting both requirements.
F = average longitudinal force kN or lbf, and
W = average vertical load kN or 1bf.
11.12 Calibrate the test wheel speed for each test tire by
bringing the vehicle up to approximately 8 km/h (5.0 mph).
12.2 Calculate the values of longitudinal slip velocity as
Place the vehicle in neutral or reduce throttle position to a follows:
minimum. Adjust the test wheel speed to be equal to vehicle
V W 2 W
~ !
o d o
V 5 (2)
speed. Care must be taken to see that the vehicle is going in a
S
W
o
straight line without tire slippage during speed calibration.
where:
11.13 Set the automatic throttle applicator to keep fore-aft
V = longitudinal slip velocity km/h or mph,
s
force increase to less than a maximum of 1780 N/s (400 lbf/s).
V = test vehicle speed km/h or mph,
o
11.14 Begin a test by activating the automatic throttle
W = spin velocity of non-driven wheel, and
o
applicator when on the test course. A straight line should be W = spin velocity of driven wheel.
d
maintained throughout testing and a smooth modulated brake
12.3 Calculate the average value of test run driving coeffi-
load applied to maintain an 8.0 6 0.8 km/h (5.0 6 0.5 mph)
cients for each test tire and the value of sample standard
test vehicle speed. In the course of testing do not use any test
deviation for ten or more test runs. Eliminate any individual
runwhenatesttiredigsthroughthebasematerialorwherethe
test run value more than 1.5 standard deviations from the
average vehicle speed is outside 8.0 6 0.8 km/h (5.0 6
calculated average.Aminimum of eight test runs shall remain.
0.5mph).
Recalculate the average and standard deviation for each test
tire.
11.15 Repeat step 11.14 a minimum of ten times. At the
completion of ten or more test runs, process the data and
12.4 Calculate the traction test coefficient of variation as
examine for a minimum of eight valid test runs after outliers
follows:
(individual test run data values more than 1.5 standard devia-
SampleStandardDeviation
tionsfromthecalculatedaverage)havebeeneliminatedandfor
C.V. 5 (3)
Mean
a calculated sample coefficient of variation (C.V.) less than
0.15 (15%). If requirements are met, record data and return to
If the data have a C.V. greater than 0.15, the tire data set
the tire changing area. Rerun the test tire if requirements are
should not be used and the entire test run shall be repeated.
not met.
13. Data Adjustment Procedures
11.16 Run a control tire at the beginning and end of each
testsequenceortestmatrixandeverythirdtestinbetween.For 13.1 The traction performance (traction coefficients) of the
example:C,T1,T2,C,T3,T4,C,whereCrepresentsacontrol candidate tires in any extended sequence of testing may vary
tire and T represents a candidate tire. due to changing environmental or other test conditions. To
F1805 − 20
evaluate traction performance without this potentially perturb- 13.5 Average Correction Method—Calculate the average
ing influence it is common practice to adjust or correct value of all control tire driving coefficients within a day’s test
candidate tire coefficients based on the values obtained for one
tire matrix. To obtain the traction performance index (TPI)
ormorecontroltirestestedthroughouttheevaluationprogram. rating, divide individual candidate tire driving traction coeffi-
cient values by the tire matrix average control tire coefficient
13.2 Practice F1650 is the reference standard that gives a
and multiply by 100 to obtain the TPI:
comprehensive b
...

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: F1805 − 18 F1805 − 20
Standard Test Method for
Single Wheel Driving Traction in a Straight Line on Snow-
and Ice-Covered Surfaces
This standard is issued under the fixed designation F1805; 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 a procedure for measuring the driving traction of passenger car and light truck tires while traveling
in a straight line on snow- or ice-covered surfaces.
1.2 This test method utilizes a dedicated, instrumented, four-wheel rear-wheel drive test vehicle with a specially instrumented
drive axle to measure fore-aft and vertical forces acting on a single driven test tire.
1.3 This test method is 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 under other environmental conditions
on other surfaces or the same surface after additional use.
1.4 The values stated in SI units are to be regarded as the standard. Ordinarily, N and kN should be used as units of force. This
standard may utilize kgf as a unit of force in order to accommodate the use of load and pressure tables, as found in other standards
both domestic and global that are commonly used with this standard. The values given in parentheses are for information only.
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, health, and environmental practices and determine the applicability of
regulatory limitations prior to use.
1.6 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
2.1 ASTM Standards:
E1136 Specification for P195/75R14 Radial Standard Reference Test Tire
F377 Practice for Calibration of Braking/Tractive Measuring Devices for Testing Tires
F538 Terminology Relating to the Characteristics and Performance of Tires
F1046 Guide for Preparing Artificially Worn Passenger and Light Truck Tires for Testing
F1572 Test Methods for Tire Performance Testing on Snow and Ice Surfaces
F1650 Practice for Evaluating Tire Traction Performance Data Under Varying Test Conditions
F2493 Specification for P225/60R16 97S Radial Standard Reference Test Tire
2.2 Other Standards:
The European Tyre and Rim Technical Organisation Standards Manual
The Japan Automobile Tyre Manufacturers Association, Inc. Yearbook
The Tire & Rim Association, Inc. Year Book
Tire Information Service Bulletin, Vol. 37/No. 56 U.S. Tire Manufacturers Association (USTMA) Definition for Passenger and
This test method is under the jurisdiction of Committee F09 on Tires and is the direct responsibility of Subcommittee F09.20 on Vehicular Testing.
Current edition approved Nov. 1, 2018May 1, 2020. Published November 2018May 2020. Originally approved in 1997. Last previous edition approved in 20162018 as
F1805 – 16.F1805 – 18. DOI: 10.1520/F1805-18.10.1520/F1805-20.
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.
Available from The European Tyre and Rim Technical Organisation, 78/80, rue Defacqz B-1060, Brussels, Belgium.
Available from The Japan Automobile Tyre Manufacturers Association, Inc., No. 33 Mori Bldg. 8th Floor, 3-8-21 Toranomon, Minato-ku, Toyko, Japan 105- 0001.
Available from The Tire & Rim Association, Inc., 175 Montrose West Ave., Suite 150, Copley, OH 44321.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
F1805 − 20
Light Truck Tires for Use in Severe Snow Conditions
3. Terminology
3.1 Definitions:
3.1.1 candidate tire, n—a test tire that is part of a test program. F538
3.1.1.1 Discussion—
The term “candidate object” may be used in the same sense as candidate tire.
3.1.2 control tire, n—a reference tire used in a specified manner throughout a test program. F538
3.1.2.1 Discussion—
A control tire may be of either type and typical tire used is the reference (control) tire in Practice F1650 that provides algorithms
for correcting (adjusting) test data for bias trend variations. (See Practice F1650. See also the discussion in 3.1.16.)
3.1.3 driving coeffıcient (nd), n—the ratio of the driving force to a normal force. F538
3.1.4 driving force (F), n— of a tire, the positive longitudinal force resulting from the application of driving torque. F538
3.1.5 grooming, v—in tire testing, mechanically reworking a snow test surface in order to obtain a surface with more consistent
properties. F538
3.1.6 ice, dry, n—smooth ice without loose surface materials. 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 longitudinal slip velocity (L/T), n— the effective rolling radius multiplied by the difference between the spin velocity (in
rad/unit time) of a driven or braked tire and that of a free rolling tire when each is traveling in a straight line. F538
3.1.9 maximum rated load, n—the load corresponding to the maximum tire load capacity at the rated inflation pressure in
accordance with the publications of tire and rim standards current at the time of manufacture. F538
3.1.10 reference tire, n—a special tire included in a test program; the test results for this tire have significance as a base value
or internal benchmark. F538
3.1.11 snow, hard pack, n— in tire testing, packed base without loose snow. F538
3.1.12 snow, medium pack, n— in tire testing, groomed packed base with 2.5 to 5.0 cm (1 to 2 in.) loose snow. F538
3.1.13 snow, medium hard pack, n— in tire testing, packed base with some loose snow. F538
3.1.14 snow, soft pack, n— in tire testing, freshly fallen or deeply groomed base snow with 5.0 to 7.5 cm (2 to 3 in.) loose snow.
F538
3.1.15 spin velocity, n—the angular velocity of the wheel about its spin axis. F538
3.1.16 standard reference test tire (SRTT), n—a tire that is used as a control tire or surface monitoring tire (for example,
Specification E1136 and Specification F2493 tires). F538
3.1.16.1 Discussion—
While ASTM designates several tire specifications as Standard Reference Test Tires, Test Method F1805 has historically used the
Specification E1136 tire as its primary reference tire and this specification is specifically identified as the control tire in the USTMA
Tire Information Service Bulletin Vol. 37/No. 5,6, which specifies requirements for application of the Severe Snow Use Symbol
(3 peak mountain snowflake).
3.1.16.2 Discussion—
ASTM has validated Specification F2493 for future use as a primary reference tire for the Severe Snow Use Symbol (3 peak
mountain snowflake). As of 2020 the Specification E1136 P195/75R14 92S Standard Reference Test Tire is expected to cease
production. Upon that occurrence, the Specification F2493 P225/60R16 97S Standard Reference Test Tire is an acceptable
replacement for the Specification E1136 SRTT.
3.1.17 surface monitoring tire, n—a reference tire used to evaluate changes in the test surface over a selected time period. F538
Available from the U.S. Tire Manufacturers Association, 1400 K Street, N.W., Washington D.C. 20005.20005, www.ustires.org/publications.
F1805 − 20
3.1.18 test (or testing), n—a procedure performed on an object (or set of nominally identical objects) using specified equipment
that produces data unique to the object (or set). F538
3.1.18.1 Discussion—
Test data are used to evaluate or model selected properties or characteristics of the object (or set of objects). The scope of testing
depends on the decisions to be made for any program, and sampling and replication plans (see definitions below) need to be
specified for a complete program description.
3.1.19 test matrix, n— in tire testing a group of candidate tires, usually with specified reference tires; all tests are normally
conducted in one testing program. F538
3.1.20 test run, n—a single pass of a loaded tire over a given test surface. F538
3.1.21 test tire, n—a tire used in a test. F538
3.1.22 test tire set, n—one or more test tires, as required by the test equipment or procedure, to perform a test, thereby producing
a single test result. F538
3.1.22.1 Discussion—
The four nominally identical tires required for vehicle stopping distance testing constitute a test tire set. In the discussion below
where the test tire is mentioned, it is assumed that the test tire set may be substituted for the test tire, if a test tire set is required
for the testing.
3.1.23 traction test, n— in tire testing, a series of n test runs at a selected operational condition; a traction test is characterized
by an average value for the measured performance parameter. F538
3.1.24 vertical load, n—the normal reaction of the tire on the road which is equal to the negative of normal force. F538
4. Summary of Test Method
4.1 These test methods describe the use of an instrumented vehicle with a single test wheel capable of measuring the tire
performance properties under drive torque on snow and ice surfaces when traveling in a straight line.
4.2 The test is conducted by driving the test vehicle over the test surface. Driving torque is gradually increased to the test wheel
while maintaining the vehicle speed by applying braking torque to the non-test wheels of the vehicle. The driving traction
coefficient is determined from the measured values of longitudinal and vertical forces over a specified slip or time range. The
recommended vehicle test speed is 8.0 km/hr (5.0 mph).
5. Significance and Use
5.1 This test method describes a technique for assessing the performance characteristics of tires in a winter environment on
snow and ice surfaces. When snow is referred to hereafter, ice is implied as appropriate.
5.2 The measured values quantify the dynamic longitudinal traction properties of tires under driving torque. Dynamic traction
properties are obtained on snow surfaces prepared in accordance with the stated test procedures and attempts to quantify the tires’
performance when integrated into a vehicle-environmental system. Changing any one of these environmental factors will change
the measurements obtained on a subsequent test run.
5.3 This test method addresses longitudinal driving traction properties only on snow and ice surfaces. Refer to Test Methods
F1572 for test methods for braking and lateral traction properties on snow or ice, or both.
6. Interferences
6.1 Factors that may affect tire snow performance and must be considered in the final analysis of data include:
6.1.1 Snow temperature,
6.1.2 Ambient temperature,
6.1.3 Mechanical breakdown of the agglomerated snowflake into granular crystals,
6.1.4 Solar load,
6.1.5 Tire temperature,
6.1.6 Tire wear condition (preparation),
6.1.7 Tire pressure,
6.1.8 Tire vertical load,
6.1.9 Snow surface characteristics, and
6.1.10 Rim selection.
F1805 − 20
7. Apparatus
7.1 The test vehicle shall have the capability of maintaining the specified test speed 6 0.8 km/h (6 0.5 mph) during all levels
of driving torque application.
7.2 The test vehicle shall be equipped with an automatic throttle actuator to allow the gradual increase of driving torque at a
predetermined (repeatable) rate.
7.3 The test vehicle shall be a rear drive, four wheel passenger car or a light truck less than or equal to 44.5 kN (10 000 lbf)
GVW. The range of test tires and load conditions will determine the vehicle size and selection. Utilizing a front wheel drive test
vehicle is not addressed in this standard although the basic procedures could be applied with appropriate conditional modifications.
7.4 The test vehicle shall be instrumented to measure longitudinal and vertical forces at the tire and test surface interface during
the application of driving torque.
7.5 The test vehicle shall have provisions to automatically and completely disengage the brake on the test wheel (if installed)
prior to throttle application. Complete disengagement is necessary to eliminate all drag that might be caused by the brake assembly.
7.6 Opposite Tire:
7.6.1 The tire installed opposite the instrumented test wheel shall have a sufficiently large traction coefficient to minimize slip
of this tire during the traction test. The opposite tire should have a coefficient at least 50 % greater than the expected coefficient
of the test tire. A tire chain may be utilized to increase the traction of the opposite tire when testing on snow surfaces.
7.6.2 The opposite tire shall be selected to have an outside diameter that is within 62.5 cm (61 in.) of that of the test tire.
7.7 A suitable ride height adjustment system on the rear axle shall be provided to permit adjustment for each tire size and load
to minimize transducer crosstalk as established during calibration.
7.8 Instrumentation—The test wheel position on the test vehicle shall be equipped with a wheel rotational velocity measuring
system and with transducers to measure the dynamic longitudinal force and vertical load at the test wheel.
7.8.1 General Requirements for Measurement System—The instrumentation system shall conform to the following overall
requirements at ambient temperatures between –23 and 43°C (–10 and 110°F):
7.8.1.1 Overall system accuracy, force—6 1.5 % of vertical load or traction force from 450 N (100 lbf) to full scale.
7.8.1.2 Overall system accuracy, speed—6 1.5 % of speed from 6.4 km/h (4.0 mph) to 48.0 km/h (30.0 mph).
7.8.1.3 Shunt Calibration—All strain-gage transducers shall be equipped with shunt calibration resistors that can be connected
before or after test runs. The calibration signal shall be in the range of the expected measurement for each analogue channel.
7.8.1.4 Ruggedness—The exposed portions of the system shall tolerate 100 % relative humidity (rain or spray) and all other
adverse conditions such as dust, shock, and vibrations which may be encountered in regular operation.
7.8.2 Vehicle Speed—Vehicle forward speed (normally obtained from a front non-driven wheel on the test vehicle) shall be
measured digitally with an encoder or optical system having a minimum of 500 counts per revolution. Output shall be directly
visible to the driver and shall be simultaneously recorded. It may be necessary on a very low coefficient surface, that is, ice, to
disconnect any braking action to the wheel being utilized for measuring vehicle speed. A separate fifth-wheel system may be
utilized to measure vehicle forward speed.
7.8.3 Test Wheel Speed—Test wheel speed shall be measured digitally with an encoder or optical system having a minimum of
1000 counts per wheel revolution. The output shall be recorded.
7.8.4 Vertical Load—The vertical load-measuring transducer shall measure the vertical load at the test wheel during driving
torque application. The transducer full scale range shall be in excess of the dynamic loading during a test. Data points shall be
evaluated to ensure dynamic loading is within the calibrated range of the transducer. The static load should be less than 80 % of
the calibrated range. The transducer design and location shall minimize inertial effects and vibration-induced mechanical
resonance. The transducer shall have an output directly proportional to the force with less than 1 % hysteresis and less than 1 %
nonlinearity at full scale. It shall have less than 2 % cross-axis sensitivity at full scale. The transducer shall be installed in such
a manner as to experience less than 1° angular rotation with respect to its measuring axes at a maximum expected driving torque.
The transducers typically have a minimum full scale range of 0 to 8.9 kN (2000 lbf).
7.8.5 Driving Traction Forces—The driving traction force-measuring transducers shall measure longitudinal force generated at
the tire-road interface as a result of driving torque application with a full scale range of at least 100 % of the applied static vertical
load. Otherwise, the transducers shall have the same specifications as those described in 7.8.4.
7.8.6 Signal Conditioning and Recording System—All signal conditioning and recording equipment shall provide linear output
with necessary gain and reading resolution to meet the requirements of 7.8.1. Additionally, it shall have the following
specifications:
7.8.6.1 Minimum Frequency Response—flat from dc to 18 Hz, within 61 %,
NOTE 1—Based on a study of a sample acquisition and force transducer system, a resonant frequency of 20 Hz was measured.
7.8.6.2 Signal-to-Noise Ratio—at least 20/1,
7.8.6.3 Gain shall be sufficient to permit full-scale display for full-scale input signal level,
7.8.6.4 Input impedance shall be at least ten times larger than the output impedance of the signal source,
F1805 − 20
7.8.6.5 The system must be insensitive to vibrations, acceleration, and changes in ambient temperature. The error in reading
shall not exceed 1 % full scale when subjected to vibration acceleration of 49.0 m/s (5 g’s) in the 0.5 to 40 Hz frequency range
and operating temperature range from –23 to 43°C (–10 to 110°F),
7.8.6.6 The system shall not be affected by storage temperature variations between –40 and 71°C (–40 and 160°F),
7.8.6.7 The individual data inputs shall have a sample rate of not less than 100 samples/s. For a given sample, vehicle speed,
test wheel speed, vertical load, and driving traction force shall all be recorded within 0.0005 s,
7.8.7 Power Supply—The power supply for transducers and recording system shall meet or exceed requirements specified by
transducer and recorder manufacturers.
7.8.8 Temperature measurement devices for taking surface and ambient temperatures shall have a resolution of 0.5°C (1°F) and
an accuracy of 61°C (62°F).
7.8.9 Pressure measurement devices for setting tire pressure shall have a resolution of 3.5 kPa ( ⁄2 psi) and an accuracy of 63.5
kPa (6 ⁄2 psi).
8. Calibration
8.1 All instrumentation shall be calibrated within six months prior to testing.
8.2 Calibrate the reference load cell by inputting known vertical and horizontal forces. The known forces must be traceable to
the National Institute of Standards and Technology (NIST).
8.3 Calibrate the transducer for measuring vertical and horizontal forces on the test wheel with the reference load cell in
accordance with Practice F377.
8.3.1 For longitudinal force calibration, place vehicle transmission in “park” position. Restrain the test vehicle using the vehicle
brakes normally used while testing.
8.4 Calibrate the vehicle and test tire speed transducers and any other instrumentation in accordance with the manufacturers’
specification.
8.5 Calibrate temperature measuring devices (snow and ambient temperatures) in accordance with the manufacturer’s
recommendations.
8.6 Calibrate pressure measuring devices in accordance with the manufacturer’s recommendations.
9. Selection and Preparation of Test Tires
9.1 Ensure all test tires are approximately the same age and stored essentially at the same conditions prior to testing unless
otherwise specified. When testing to the requirements of the latest version of Tire Information Service Bulletin Vol. 37/No. 5, 37,
the SRTT Specification E1136 (or Specification F2493) control tire shall be less than 2 years old based on the week/year
manufacture date molded into the tire sidewall.
9.2 Test tires shall have no evidence of force or run-out grinding.
9.3 New test tires shall be trimmed to remove all protuberances in the tread area caused by mold air vents or flashing at mold
junctions.
9.4 Any objects (for example, shipping labels) in the tread area shall be removed prior to testing.
9.5 Tires that have been buffed to simulate wear must be prepared and run until all evidence of buffing is removed in accordance
with Guide F1046.
9.6 Mount the test tires on rims specified by the appropriate tire and rim standards organization, using conventional mounting
methods. Ensure proper bead seating by the use of a suitable lubricant. Excessive use of lubricant should be avoided to prevent
slipping of the tire on the wheel rim. Ensure tires are mounted so the intended rotational direction of the tire corresponds with the
test wheel position of the test vehicle. If rotation direction of the tire is not specified, the tire shall be mounted so during testing
it rotates clockwise when viewed from the intended outboard sidewall of the tire.
9.7 Test tire balance is not necessary.
9.8 New test tire break-in is optional, however, the design of the test may necessitate on-the-road conditioning of up to 322 km
(200 miles). Tire break-in may improve repeatability of results on ice surfaces.
9.9 Mounted test tires shall be placed near the test site in such a location that they all have the same temperature prior to testing.
Test tires should be shielded from the sun to avoid excessive heating by solar radiation.
9.10 Test tires shall be checked and adjusted for specified pressure just prior to testing.
10. Preparation of Apparatus
10.1 All transducers and instrumentation shall have been calibrated in accordance with Section 8.
10.2 Turn on the test vehicle instrumentation and allow it to warm up as required for stabilization.
F1805 − 20
10.3 Ensure the test vehicle has sufficient fuel to complete a test matrix.
10.4 Maneuver the test vehicle to the tire changing area.
10.5 Position the temperature measurement devices.
10.6 Allow sufficient time to ensure that the temperatures of all equipment have stabilized.
10.7 Set the front speed reference tire or fifth wheel to the pressure utilized during the speed calibration 63.5 kPa (60.5 psi).
Non-test rear tire pressures should be set as appropriate.
10.8 Perform a resistive shunt calibration on the force transducers once per day at a minimum. It is recommended that a resistive
shunt calibration check be performed at the start and end of each testing day.
11. Procedure
11.1 Course Surface—See Annex A1 – Annex A4 for environmental and snow properties, surface characterization, course
preparation, and course maintenance. When testing to the requirements of the Tire Information Service Bulletin Vol. 37/No. 5,6,
a medium-packed snow surface shall be used.
11.2 Lift the rear axle so that the rear tires are off the ground.
11.3 Install a control or candidate tire at the test wheel position with the vehicle jacked up.
11.4 Opposite the test wheel position install a tire that has an outside diameter within 62.5 cm (61 in.) of the test tire. A chained
tire is optional in snow.
11.5 Record basic test information and tire conditions. Ambient and surface temperatures shall be updated with each control tire.
11.6 With the transmission in park or neutral, tare vertical load and tractive force by zeroing the signals.
11.7 Verify the vehicle and test wheel speeds are zero.
11.8 Lower the rear axle, placing the tires on the ground.
11.9 Ballast the test tire for the desired load, 622 N (65 lbf), and set the tire to the specified test inflation pressure, 63.5 kPa
(60.5 psi). One of the following three options shall be selected for determining load and inflation pressure for testing. The option
selected shall be noted in the final report. If computed test load exceeds the test equipment capabilities, test inflation rated load
TABLE 1 Test Load and Test Pressure Options
F1805
F1805 Marked Sidewall F1805
Tire Type Test Pressure
Test Option max psi Test Load
psi
1 Passenger car tire Any 70 % of Maximum rated load 36
(TRA/ETRTO/JATMA) or 567 kgf (1250 lbf) max
Light Truck Any 70 % of Maximum rated load 51
(TRA/ETRTO/JATMA) or 567 kgf (1250 lbf) max
2 Pmetric LL,SL 35 74 % * table value 35
at test pressure
44 74 % * table value 35
at test pressure
51 74 % * table value 35
at test pressure
Pmetric XL 41 74 % * table value 41
at test pressure
50 74 % * table value 41
at test pressure
LT-metric 74 % * table value 50
at test pressure
Flotation-LT 74 % * table value 35
at test pressure
Eurometric C (Commercial LT) 74 % * table value 51
at test pressure
Eurometric SL 32 74 % * table value 32
at test pressure
36 74 % * table value 36
at test pressure
44 74 % * table value 36
at test pressure
51 74 % * table value 36
at test pressure
Eurometric XL 42 74 % * table value 42
at test pressure
51 74 % * table value 42
at test pressure
3 Any Any Any
F1805 − 20
and its corresponding pressure may be reduced to the next lower load/pressure increment and a new test load/pressure recomputed.
See Annex A5 for examples of load and pressure determination for options 1 and 2. Table 1 summarizes the various test load and
pressure options.
NOTE 2—A P195/75R14 SRTT (Specification E1136) control tire is tested at a load of 468 kgf (1031 lbf) and a pressure of 240 kPa (35 psi). A
P225/60R16 SRTT (Specification F2493) control tire is tested at a load of 531 kgf (1171 lbf) and a pressure of 240 kPa (35 psi).
11.9.1 Option 1—The test load for passenger car tires shall be the lower value of 70 % of the maximum rated load of the tire
or 567 kgf (1250 lbf). The test load for light truck tires shall be the lower value of 70 % of the maximum rated load of the tire
or 567 kgf (1250 lbf). An inflation pressure of 250 kPa (36 psi) shall be used for passenger tires and 350 kPa (51 psi) shall be used
for light truck tires.
11.9.2 Option 2—The test load shall be equal to 74 % of the rated load at the test inflation pressure as shown in the Tire & Rim
Association (TRA) Year Book, in the European Tyre and Rim Technical Organisation Manual (ETRTO), or in the Japan
Automobile Tyre Manufacturers Association Manual (JATMA). See Table 1. This option meets the requirement for equivalent
percentage loads as specified in the USTMA Tire Information Service Bulletin Vol. 37/No. 5.6.
11.9.3 Option 3—The test tire loads and inflation pressures shall be any other loads and pressures required to meet the individual
requirements of a specific test program.
11.10 Adjust the vehicle ride height to the value established during the calibration for minimum crosstalk taking into account
differences in tire dimensions.
11.11 Re-verify test load. Adjusting vehicle ride height may change the test load. Several load/ride height adjustments may be
necessary before meeting both requirements.
11.12 Calibrate the test wheel speed for each test tire by bringing the vehicle up to approximately 8 km/h (5.0 mph). Place the
vehicle in neutral or reduce throttle position to a minimum. Adjust the test wheel speed to be equal to vehicle speed. Care must
be taken to see that the vehicle is going in a straight line without tire slippage during speed calibration.
11.13 Set the automatic throttle applicator to keep fore-aft force increase to less than a maximum of 1780 N/s (400 lbf/s).
11.14 Begin a test by activating the automatic throttle applicator when on the test course. A straight line should be maintained
throughout testing and a smooth modulated brake load applied to maintain an 8.0 6 0.8 km/h (5.0 6 0.5 mph) test vehicle speed.
In the course of testing do not use any test run when a test tire digs through the base material or where the average vehicle speed
is outside 8.0 6 0.8 km/h (5.0 6 0.5 mph).
11.15 Repeat step 11.14 a minimum of ten times. At the completion of ten or more test runs, process the data and examine for
a minimum of eight valid test runs after outliers (individual test run data values more than 1.5 standard deviations from the
calculated average) have been eliminated and for a calculated sample coefficient of variation (C.V.) less than 0.15 (15 %). If
requirements are met, record data and return to the tire changing area. Rerun the test tire if requirements are not met.
11.16 Run a control tire at the beginning and end of each test sequence or test matrix and every third test in between. For
example: C, T1, T2, C, T3, T4, C, where C represents a control tire and T represents a candidate tire.
NOTE 3—A single control or candidate tire may be used repeatedly as long as the tread surface maintains a “new” appearance.
11.17 Each candidate tire should be tested at least three times, preferably on different days.
11.18 Each new test tire shall be run on a surface as near as possible to the previous pass. Care must be taken not to allow the
test tire to drift into disturbed snow used during previous test runs.
11.19 Testing continues until the total test sequences or test matrix is completed or the available test surface is exhausted.
Regrooming the course will normally allow testing to continue.
12. Calculation
12.1 For each test run of each control and candidate tire, read from accumulated data the values of longitudinal force and
vertical load corresponding to the values of longitudinal slip velocity within the range 1.6 and 24 km/h (1 and 15 mph) or a range
starting at 3.2 km/h (2 mph) and continuing for 1.5 s. Calculate the average force and load values over the specified slip or time
range. Calculate the average values of driving coefficient as follows:
F
u 5 (1)
W
where:
u = average driving coefficient,
F = average longitudinal force kN or lbf, and
W = average vertical load kN or 1bf.
12.2 Calculate the values of longitudinal slip velocity as follows:
F1805 − 20
V W 2 W
~ !
o d o
V 5 (2)
S
W
o
where:
V = longitudinal slip velocity km/h or mph,
s
V = test vehicle speed km/h or mph,
o
W = spin velocity of non-driven wheel, and
o
W = spin velocity of driven wheel.
d
12.3 Calculate the average value of test run driving coefficients for each test tire and the value of sample standard deviation for
ten or more test runs. Eliminate any individual test run value more than 1.5 standard deviations from the calculated average. A
minimum of eight test runs shall remain. Recalculate the average and standard deviation for each test tire.
12.4 Calculate the traction test coefficient of variation as follows:
Sample Standard Deviation
C.V.5 (3)
Mean
If the data have a C.V. greater than 0.15, the tire data set should not be used and the entire test run shall be repeated.
13. Data Adjustment Procedures
13.1 The traction performance (traction coefficients) of the candidate tires in any extended sequence of testing may vary due
to changing environmental or other test conditions. To evaluate traction performance without this potentially perturbing influence
it is common practice to adjust or correct candidate tire coefficients based on the values obtained for one or more control tires tested
throughout the evaluation program.
13.2 Practice F1650 is the reference standard that gives a comprehensive background and recommended control and candidate
tire test sequence as well as procedures for making these corrections. (See Section 7.) Practice F1650 permits corrections to be
made if there is any significant time trend or other perturbation in environmental or other testing conditions during the testing
program.
13.3 Other correction procedures are al
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