ASTM F1572-08(2015)

Standard Test Methods for Tire Performance Testing on Snow and Ice Surfaces

SIGNIFICANCE AND USE
5.1 These test methods describe techniques for assessing the performance characteristics of tires in a winter environment on snow and ice surfaces in a standardized manner. When only snow is referred to hereafter, it should be understood that ice is implied as appropriate.  
5.2 A series of maneuvers are conducted to characterize several aspects of the tire performance in snow, since a single maneuver is not sufficient to characterize all aspects of a tire's performance.
SCOPE
1.1 These test methods cover the evaluation of tire performance on snow and ice surfaces utilizing passenger car or light truck vehicles. Since the tires are evaluated as part of a tire/vehicle system, the conclusions reached may not be applicable to the same tires tested on a different vehicle.  
1.2 These test methods do not purport to identify every maneuver useful for determining tire performance in a winter environment.  
1.3 These test methods are not meant to evaluate vehicle performance. Allowing for the variability of test results with different vehicles, these procedures have been developed and selected to evaluate relative tire-snow performance.  
1.4 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 under other environmental conditions on other surfaces or the same surface after additional use.  
1.5 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.  
1.6 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.

General Information

• Status: Historical
• Publication Date: 30-Apr-2015
• ICS: 83.160.10 - Road vehicle tyres
• Technical Committee: F09 - Tires
• Drafting Committee: F09.20 - Vehicular Testing

Standards Content (Sample)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation: F1572 − 08 (Reapproved 2015)
Standard Test Methods for
Tire Performance Testing on Snow and Ice Surfaces
This standard is issued under the fixed designation F1572; 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 E1136Specification for P195/75R14 Radial Standard Refer-
ence Test Tire
1.1 These test methods cover the evaluation of tire perfor-
F457Test Method for Speed and Distance Calibration of
manceonsnowandicesurfacesutilizingpassengercarorlight
Fifth Wheel Equipped With Either Analog or Digital
truck vehicles. Since the tires are evaluated as part of a
Instrumentation
tire/vehicle system, the conclusions reached may not be appli-
F538Terminology Relating to the Characteristics and Per-
cable to the same tires tested on a different vehicle.
formance of Tires
1.2 These test methods do not purport to identify every
F811Practice for Accelerometer Use in Vehicles for Tire
maneuver useful for determining tire performance in a winter
Testing
environment.
F1046Guide for Preparing Artificially Worn Passenger and
1.3 These test methods are not meant to evaluate vehicle Light Truck Tires for Testing
F1650Practice for Evaluating Tire Traction Performance
performance. Allowing for the variability of test results with
different vehicles, these procedures have been developed and Data Under Varying Test Conditions
F1805Test Method for Single Wheel Driving Traction in a
selected to evaluate relative tire-snow performance.
Straight Line on Snow- and Ice-Covered Surfaces
1.4 These test methods are suitable for research and devel-
2.2 SAE Standards:
opment purposes, where tires are compared during a single
SAE J1466Passenger Car and Light Truck Tire Dynamic
series of tests.They may not be suitable for regulatory statutes
Driving Traction in Snow
or specification acceptance because the values obtained may
not necessarily agree or correlate either in rank order or
3. Terminology
absolute traction performance level with those obtained under
other environmental conditions on other surfaces or the same 3.1 Definitions:
3.1.1 candidate tire, n—a test tire that is part of a test
surface after additional use.
program.
1.5 The values stated in SI units are to be regarded as the
3.1.1.1 Discussion—The term “candidate object” may be
standard. The values given in parentheses are for information
used in the same sense as candidate tire. F538
only.
3.1.2 candidate tire set, n—a set of candidate tires. F538
1.6 This standard does not purport to address all of the
3.1.3 control tire, n—a reference tire used in a specified
safety concerns, if any, associated with its use. It is the
manner throughout a test program.
responsibility of the user of this standard to establish appro-
3.1.3.1 Discussion—Acontroltiremaybeofeithertypeand
priate safety and health practices and determine the applica-
typical tire use is the reference (control) tire in Practice F1650
bility of regulatory limitations prior to use.
that provides algorithms for correcting (adjusting) test data for
2. Referenced Documents biastrendvariations(SeePracticeF1650andAnnexA1). F538
3.1.4 driving coeffıcient (nd), n—the ratio of the driving
2.1 ASTM Standards:
force to a normal force. F538
E178Practice for Dealing With Outlying Observations
3.1.5 driving force (F), n— of a tire, the positive longitudi-
nalforceresultingfromtheapplicationofdrivingtorque. F538
ThesetestmethodsareunderthejurisdictionofASTMCommitteeF09onTires
3.1.6 grooming, v—in tire testing,mechanicallyreworkinga
and are the direct responsibility of Subcommittee F09.20 on Vehicular Testing.
Current edition approved May 1, 2015. Published June 2015. Originally
snow test surface in order to obtain a surface with more
approved in 1994. Last previous edition approved in 2008 as F1572–08. DOI:
consistent properties. F538
10.1520/F1572-08R15.
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 AvailablefromSAEAutomotiveHeadquarters,755W.BigBeaver,Suite1600,
the ASTM website. Troy, MI 48084.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
F1572 − 08 (2015)
3.1.7 ice, dry, n—smooth ice without loose surface 4. Summary of Test Method
materials. F538
4.1 These test methods describe a series of vehicle maneu-
3.1.8 longitudinal force (F), n— of a tire, the component of
vers which can be utilized by the tire and vehicle industry to
the tire force vector in the X' direction. F538
consistently measure the properties of a tire’s performance on
snow and ice surfaces in the braking, driving and cornering
3.1.9 longitudinal slip velocity (L/T), n— the effective
traction modes.
rolling radius multiplied by the difference between the spin
velocity (in rad/unit time) of a driven or braked tire and that of
4.2 These test methods outline the procedures for conduct-
afreerollingtirewheneachistravelinginastraightline. F538
ing the following tests:
4.2.1 Road circuit handling,
3.1.10 reference tire, n—a special tire included in a test
4.2.2 Winter hill climb,
program;thetestresultsforthistirehavesignificanceasabase
4.2.3 Winter slalom,
value or internal benchmark. F538
4.2.4 Acceleration—straight ahead,
3.1.11 snow, hard pack, n— in tire testing, packed base
4.2.5 Braking—straight ahead, and
without loose snow. F538
4.2.6 Step steer.
3.1.12 snow, medium hard pack, n— in tire testing, packed
base with some loose snow.
5. Significance and Use
3.1.13 snow, medium pack, n— in tire testing, groomed
5.1 Thesetestmethodsdescribetechniquesforassessingthe
packed base with 2.5 to 5.0 cm (1 to 2 in.) loose snow. F538
performancecharacteristicsoftiresinawinterenvironmenton
3.1.14 snow, soft pack, n— in tire testing, freshly fallen or
snow and ice surfaces in a standardized manner. When only
deeplygroomedbasesnowwith5.0to7.5cm(2to3in.)loose
snowisreferredtohereafter,itshouldbeunderstoodthaticeis
snow. F538
implied as appropriate.
3.1.15 spin velocity, n—the angular velocity of the wheel
5.2 A series of maneuvers are conducted to characterize
about its spin axis. F538
several aspects of the tire performance in snow, since a single
maneuver is not sufficient to characterize all aspects of a tire’s
3.1.16 standard reference test tire (SRTT), n—a tire that
performance.
meets the requirements of Specification E1136, commonly
used as control tire or a surface monitoring tire.
6. Interferences
3.1.16.1 Discussion—This is a Type 1 reference tire. F538
3.1.16.2 Discussion—Asurface monitoring tire may also be
6.1 Factors which may affect tire snow performance and
used as a control tire.
must be considered in the final analysis of data include:
3.1.17 surface monitoring tire, n—a reference tire used to 6.1.1 Snow/ambient temperature,
6.1.2 Mechanical breakdown of snowflake into granular
evaluate changes in a test surface over a selected time period.
F538 crystals,
6.1.3 Solar heat load and tire temperature,
3.1.18 test (or testing), n—a procedure performed on an
6.1.4 Tire wear condition or preparation,
object (or set of nominally identical objects) using specified
6.1.5 Tire pressure and vertical load,
equipment that produces data unique to the object (or set).
6.1.6 Test vehicle characteristics,
3.1.18.1 Discussion—Test data are used to evaluate or
6.1.7 Snow surface characteristics,
modelselectedpropertiesorcharacteristicsoftheobject(orset
6.1.8 Test driver, and
ofobjects).Thescopeoftestingdependsonthedecisionstobe
6.1.9 Rim selection.
madeforanyprogram,andsamplingandreplicationplans(see
definitions below) need to be specified for a complete program
7. Apparatus
description. F538
7.1 Duetothenatureofthesetestmethods,specificrequire-
3.1.19 test matrix, n— in tire testing a group of candidate
ments for apparatus will be limited. A general discussion of
tires, usually with specified reference tires; all tests are
types of apparatus and their uses follows.
normally conducted in one testing program.
7.1.1 Time Measurement—Thisprovidesoneofthesimplest
3.1.20 test tire, n—a tire used in a test. F538
and lowest cost methods of quantifying tire performance.
3.1.21 test tire set, n—one or more test tires as required by
However, since time measurement inherently involves averag-
the test equipment or procedure, to perform a test, thereby
ing over a time period, the measurements obtained provide
producing a single test result.
only a general overview of performance.
3.1.21.1 Discussion—The four nominally identical tires re-
7.1.1.1 Time measurement apparatus may be onboard the
quiredforvehiclestoppingdistancetestingconstituteatesttire
vehicle or stationary and may vary from handheld stopwatches
set. In the discussion below where the test tire is mentioned, it
to optical start/stop gates or combined apparatus for measure-
is assumed that the test tire set may be submitted for test tire,
ment of time and other properties (for example, fifth wheel
if a test tire set is required for the testing. F538
apparatus).
3.1.22 vertical load, n—the normal reaction of the tire on 7.1.1.2 Many tests measure time to complete a slalom or
the road which is equal to the negative of normal force. F538 hill-and-curve course. Other tests involve measuring the time
F1572 − 08 (2015)
necessary to reach some condition, such as the time necessary moving the system to a different test site. Telemetry is not
to stop from a given speed or the time to achieve a certain widely used at present but may be of value in the future.
speed from rest. 7.1.3 Acceleration Measurement—Acceleration measure-
7.1.2 Speed and Distance Measurement—Vehicle speed and ment is a primary technology used for evaluating tire snow
performance. Due to their low cost and ease of mounting,
distance measurement may be used for evaluating tire snow
performance. There are a number of technologies for measur- three-axis accelerometers provide a simple way to evaluate
some aspects of tire performance.
ing speed and distance.
7.1.3.1 Accelerometers function by measuring the accelera-
7.1.2.1 Fifth Wheel Based—This test method requires that a
tion of a vehicle. This acceleration depends on the forces
lightly loaded free-rolling wheel be attached to the vehicle. A
existing at the tire/surface interface.
revolution counting device on this wheel is used to provide
7.1.3.2 Accelerometers typically have bandwidths in excess
typical distance resolutions of 1 cm (0.4 in.). Fifth wheel type
of 100 Hz, allowing dynamic measurement of forces in a
devicesarehighlyreliablebutmaysliponlowfrictionsurfaces
handling test.
orbounceonaroughsurface,providinginaccuratereadings.A
7.1.3.3 Drawbacks to the use of accelerometers include:
fifth wheel may not be appropriate on a road circuit handling
sensitivity to wind and vehicle orientation changes, such as
course. Fifth wheel type devices are not suitable for use in
body pitch and roll, which occur in handling maneuvers
radical maneuvers or situations where the vehicle may slide or
(gyro-stabilized platforms can be used to eliminate this prob-
spinout, as these maneuvers may cause damage to the devices.
lem); the need to mount the accelerometer at or near the center
See Test Method F457 for additional information on fifth
of gravity of the test vehicle to obtain accurate data; the fact
wheels.
that accelerations on snow and ice surfaces are typically small
7.1.2.2 Non-Contact Optical—Optical sensors are available
in magnitude; and the fact that accelerometer signals are
which can measure both longitudinal and lateral speed. Since
typically noisy, leading to the need for filtration of the signal.
these sensors do not contact the road surface they may be used
See Practice F811 for additional accelerometer usage informa-
without damage in tests which may involve spinouts or
tion.
significant lateral motion. However, optical sensors depend on
7.1.4 Vehicle Orientation—Devices to measure vehicle ori-
surface microtexture and they may not work on all surface
entation include gyroscopes, wheel steer angle transducers and
conditions.
some telemetry systems.
7.1.2.3 Wheel Speed—A wheel speed sensing device (opti-
7.1.4.1 Measurement of the test vehicle’s orientation about
cal encoder or tachometer) mounted on the wheels of the test
its pitch and roll axis is typically used for correction of
vehicle permits the measurement of rotational speed of the
accelerometer based test systems.
wheels and the calculation of distance traveled. These test
7.1.4.2 Measurement of the test vehicle’s orientation about
methods may be prone to error due to wheel slip or changing
itsyawaxisaswellaswheelsteeranglemeasurementareused
rolling radius. Wheel speed sensors are usually used in
in cornering performance testing.
conjunction with 7.1.2.1 or 7.1.2.2 to determine the extent of
7.1.4.3 Due to high cost, vehicle orientation measurement
wheel spin.
devicesaretypicallyusedonlyontestsrequiringahighdegree
7.1.2.4 Accelerometers—Several commercial performance
of accuracy.
computers exist which calculate speed and distance traveled
7.1.5 Force—Direct measurement of tire/surface forces is
based on internally mounted accelerometers. These devices
normally accomplished using load cells.
perform numerical integration to compute speed and distance
7.1.5.1 Load cells provide the most accurate measure of tire
from the acceleration signal. Accelerometer-based devices are
forces under dynamic conditions.
non-contact and self-contained; they are easy to transfer
7.1.5.2 Using specially designed suspensions, load cell
between vehicles. These devices are best suited to tests which
basedsystemsmaybebuiltwhicharenotsignificantlyaffected
involve primarily straight ahead motion and which involve
by body roll of the test vehicle.
events of short duration.
7.1.5.3 Due to mounting requirements, load cell-based sys-
7.1.2.5 Radar—Self-contained radio and microwave speed
tems typically are not easily transferred between multiple
sensing devices are not widely used for tire performance
vehicles.
testing. Development of these devices is continuing.
7.1.2.6 Telemetry—Vehicle position sensing equipment is
8. Selection and Preparation of Test Tires
available which utilizes both stationary and vehicle mounted
8.1 Ensure that all test tires are approximately the same age
transceivers. Using multiple stationary antennae, this equip-
and stored essentially at the same conditions prior to testing
ment
...

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: F1572 − 08 F1572 − 08 (Reapproved 2015)
Standard Test Methods for
Tire Performance Testing on Snow and Ice Surfaces
This standard is issued under the fixed designation F1572; 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 These test methods cover the evaluation of tire performance on snow and ice surfaces utilizing passenger car or light truck
vehicles. Since the tires are evaluated as part of a tire/vehicle system, the conclusions reached may not be applicable to the same
tires tested on a different vehicle.
1.2 These test methods do not purport to identify every maneuver useful for determining tire performance in a winter
environment.
1.3 These test methods are not meant to evaluate vehicle performance. Allowing for the variability of test results with different
vehicles, these procedures have been developed and selected to evaluate relative tire-snow performance.
1.4 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 under other environmental
conditions on other surfaces or the same surface after additional use.
1.5 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.
1.6 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.
2. Referenced Documents
2.1 ASTM Standards:
E178 Practice for Dealing With Outlying Observations
E1136 Specification for P195/75R14 Radial Standard Reference Test Tire
F457 Test Method for Speed and Distance Calibration of Fifth Wheel Equipped With Either Analog or Digital Instrumentation
F538 Terminology Relating to the Characteristics and Performance of Tires
F811 Practice for Accelerometer Use in Vehicles for Tire Testing
F1046 Guide for Preparing Artificially Worn Passenger and Light Truck Tires for Testing
F1650 Practice for Evaluating Tire Traction Performance Data Under Varying Test Conditions
F1805 Test Method for Single Wheel Driving Traction in a Straight Line on Snow- and Ice-Covered Surfaces
2.2 SAE Standards:
SAE J1466 Passenger Car and Light Truck Tire Dynamic Driving Traction in Snow
3. Terminology
3.1 Definitions:
3.1.1 candidate tire, n—a test tire that is part of a test program.
These test methods are under the jurisdiction of ASTM Committee F09 on Tires and are the direct responsibility of Subcommittee F09.20 on Vehicular Testing.
Current edition approved Oct. 1, 2008May 1, 2015. Published December 2008June 2015. Originally approved in 1994. Last previous edition approved in 20052008 as
F1572 – 99 (2005).F1572 – 08. DOI: 10.1520/F1572-08.10.1520/F1572-08R15.
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 SAE Automotive Headquarters, 755 W. Big Beaver, Suite 1600, Troy, MI 48084.
3.1.1.1 Discussion—
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
F1572 − 08 (2015)
The term “candidate object” may be used in the same sense as candidate tire. F538
3.1.2 candidate tire set, n—a set of candidate tires. F538
3.1.3 control tire, n—a reference tire used in a specified manner throughout a test program.
3.1.3.1 Discussion—
A control tire may be of either type and typical tire use is the reference (control) tire in Practice F1650 that provides algorithms
for correcting (adjusting) test data for bias trend variations (See Practice F1650 and Annex A1). F538
3.1.4 driving coeffıcient (nd), n—the ratio of the driving force to a normal force. F538
3.1.5 driving force (F), n— of a tire, the positive longitudinal force resulting from the application of driving torque. F538
3.1.6 grooming, v—in tire testing, mechanically reworking a snow test surface in order to obtain a surface with more consistent
properties. F538
3.1.7 ice, dry, n—smooth ice without loose surface materials. F538
3.1.8 longitudinal force (F), n— of a tire, the component of the tire force vector in the X' direction. F538
3.1.9 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
3.1.10 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 hard pack, n— in tire testing, packed base with some loose snow.
3.1.13 snow, medium pack, n— in tire testing, groomed packed base with 2.5 to 5.0 cm (1 to 2 in.) loose snow. F538
3.1.14 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 meets the requirements of Specification E1136, commonly used as
control tire or a surface monitoring tire.
3.1.16.1 Discussion—
This is a Type 1 reference tire. F538
3.1.16.2 Discussion—
A surface monitoring tire may also be used as a control tire.
3.1.17 surface monitoring tire, n—a reference tire used to evaluate changes in a test surface over a selected time period. F538
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).
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. F538
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.
3.1.20 test tire, n—a tire used in a test. F538
3.1.21 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.
3.1.21.1 Discussion—
The four nominally identical tires required for vehicle stopping distance testing constitute a test tire set. In the discussion below
F1572 − 08 (2015)
where the test tire is mentioned, it is assumed that the test tire set may be submitted for test tire, if a test tire set is required for
the testing. F538
3.1.22 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 a series of vehicle maneuvers which can be utilized by the tire and vehicle industry to
consistently measure the properties of a tire’s performance on snow and ice surfaces in the braking, driving and cornering traction
modes.
4.2 These test methods outline the procedures for conducting the following tests:
4.2.1 Road circuit handling,
4.2.2 Winter hill climb,
4.2.3 Winter slalom,
4.2.4 Acceleration—straight ahead,
4.2.5 Braking—straight ahead, and
4.2.6 Step steer.
5. Significance and Use
5.1 These test methods describe techniques for assessing the performance characteristics of tires in a winter environment on
snow and ice surfaces in a standardized manner. When only snow is referred to hereafter, it should be understood that ice is implied
as appropriate.
5.2 A series of maneuvers are conducted to characterize several aspects of the tire performance in snow, since a single maneuver
is not sufficient to characterize all aspects of a tire’s performance.
6. Interferences
6.1 Factors which may affect tire snow performance and must be considered in the final analysis of data include:
6.1.1 Snow/ambient temperature,
6.1.2 Mechanical breakdown of snowflake into granular crystals,
6.1.3 Solar heat load and tire temperature,
6.1.4 Tire wear condition or preparation,
6.1.5 Tire pressure and vertical load,
6.1.6 Test vehicle characteristics,
6.1.7 Snow surface characteristics,
6.1.8 Test driver, and
6.1.9 Rim selection.
7. Apparatus
7.1 Due to the nature of these test methods, specific requirements for apparatus will be limited. A general discussion of types
of apparatus and their uses follows.
7.1.1 Time Measurement—This provides one of the simplest and lowest cost methods of quantifying tire performance. However,
since time measurement inherently involves averaging over a time period, the measurements obtained provide only a general
overview of performance.
7.1.1.1 Time measurement apparatus may be onboard the vehicle or stationary and may vary from handheld stopwatches to
optical start/stop gates or combined apparatus for measurement of time and other properties (for example, fifth wheel apparatus).
7.1.1.2 Many tests measure time to complete a slalom or hill-and-curve course. Other tests involve measuring the time necessary
to reach some condition, such as the time necessary to stop from a given speed or the time to achieve a certain speed from rest.
7.1.2 Speed and Distance Measurement—Vehicle speed and distance measurement may be used for evaluating tire snow
performance. There are a number of technologies for measuring speed and distance.
7.1.2.1 Fifth Wheel Based—This test method requires that a lightly loaded free-rolling wheel be attached to the vehicle. A
revolution counting device on this wheel is used to provide typical distance resolutions of 1 cm (0.4 in.). Fifth wheel type devices
are highly reliable but may slip on low friction surfaces or bounce on a rough surface, providing inaccurate readings. A fifth wheel
may not be appropriate on a road circuit handling course. Fifth wheel type devices are not suitable for use in radical maneuvers
or situations where the vehicle may slide or spinout, as these maneuvers may cause damage to the devices. See Test Method F457
for additional information on fifth wheels.
7.1.2.2 Non-Contact Optical—Optical sensors are available which can measure both longitudinal and lateral speed. Since these
sensors do not contact the road surface they may be used without damage in tests which may involve spinouts or significant lateral
motion. However, optical sensors depend on surface microtexture and they may not work on all surface conditions.
7.1.2.3 Wheel Speed—A wheel speed sensing device (optical encoder or tachometer) mounted on the wheels of the test vehicle
permits the measurement of rotational speed of the wheels and the calculation of distance traveled. These test methods may be
F1572 − 08 (2015)
prone to error due to wheel slip or changing rolling radius. Wheel speed sensors are usually used in conjunction with 7.1.2.1 or
7.1.2.2 to determine the extent of wheel spin.
7.1.2.4 Accelerometers—Several commercial performance computers exist which calculate speed and distance traveled based
on internally mounted accelerometers. These devices perform numerical integration to compute speed and distance from the
acceleration signal. Accelerometer-based devices are non-contact and self-contained; they are easy to transfer between vehicles.
These devices are best suited to tests which involve primarily straight ahead motion and which involve events of short duration.
7.1.2.5 Radar—Self-contained radio and microwave speed sensing devices are not widely used for tire performance testing.
Development of these devices is continuing.
7.1.2.6 Telemetry—Vehicle position sensing equipment is available which utilizes both stationary and vehicle mounted
transceivers. Using multiple stationary antennae, this equipment may provide dynamic vehicle position, speed and orientation data
with great accuracy. The disadvantages to this approach are the cost of the systems and the difficulty in moving the system to a
different test site. Telemetry is not widely used at present but may be of value in the future.
7.1.3 Acceleration Measurement—Acceleration measurement is a primary technology used for evaluating tire snow perfor-
mance. Due to their low cost and ease of mounting, three-axis accelerometers provide a simple way to evaluate some aspects of
tire performance.
7.1.3.1 Accelerometers function by measuring the acceleration of a vehicle. This acceleration depends on the forces existing at
the tire/surface interface.
7.1.3.2 Accelerometers typically have bandwidths in excess of 100 Hz, allowing dynamic measurement of forces in a handling
test.
7.1.3.3 Drawbacks to the use of accelerometers include: sensitivity to wind and vehicle orientation changes, such as body pitch
and roll, which occur in handling maneuvers (gyro-stabilized platforms can be used to eliminate this problem); the need to mount
the accelerometer at or near the center of gravity of the test vehicle to obtain accurate data; the fact that accelerations on snow and
ice surfaces are typically small in magnitude; and the fact that accelerometer signals are typically noisy, leading to the need for
filtration of the signal. See Practice F811 for additional accelerometer usage information.
7.1.4 Vehicle Orientation—Devices to measure vehicle orientation include gyroscopes, wheel steer angle transducers and some
telemetry systems.
7.1.4.1 Measurement of the test vehicle’s orientation about its pitch and roll axis is typically used for correction of
accelerometer based test systems.
7.1.4.2 Measurement of the test vehicle’s orientation about its yaw axis as well as wheel steer angle measurement are used in
co
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