ASTM F2779-10(2016)

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: F2779 − 10 (Reapproved 2016)
Standard Practice for
Commercial Radial Truck-Bus Tires to Establish Equivalent
Test Severity Between a 1.707-m (67.23-in.) Diameter
Roadwheel and a Flat Surface
This standard is issued under the fixed designation F2779; 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 typical commercial truck and bus tires. See Section 7 and
2,3
References (1, 2) for more details.
1.1 This practice describes the procedure to identify equiva-
1.2.1 For users viewing the standard on CD-ROM or PDF,
lent test severity conditions between a 1.707-m diameter
with an active and working internet connection, the profilers
laboratory roadwheel surface and a flat or highway surface for
can be accessed on theASTM website by clicking on the links
commercial radial truck-bus tires.
in 7.5 and 7.6.
1.1.1 Tire operational severity, as defined as the running or
1.2.2 For users viewing the standard in a printed format, the
operational temperature for certain specified internal tire
profilers can be accessed by entering the links to the ASTM
locations, is not the same for these two test conditions. It is
website in 7.5 and 7.6 into their internet browsers.
typically higher for the laboratory roadwheel at equal load,
1.3 For this standard, SI units shall be used, except where
speed and inflation pressure conditions due to the curvature
indicated.
effect.
1.4 This standard does not purport to address all of the
1.1.2 Thepracticeappliestospecificoperatingconditionsof
safety concerns, if any, associated with its use. It is the
load range F through L for such commercial radial truck-bus
responsibility of the user of this standard to establish appro-
tires.
priate safety and health practices and determine the applica-
1.1.3 The specific operating conditions under which the
bility of regulatory limitations prior to use.
procedures of the practice are valid and useful are completely
outlined in Section 6 (Limitations) of this standard.
2. Referenced Documents
1.1.4 Itisimportanttonotethatthisstandardiscomposedof
2.1 ASTM Standards:
two distinct formats:
F538 Terminology Relating to the Characteristics and Per-
1.1.4.1 The usual text format as published in this volume of
formance of Tires
the Book of Standards (Vol 09.02).
F551 Practice for Using a 67.23-in. (1.707-m) Diameter
Laboratory Test Roadwheel in Testing Tires
1.1.4.2 A special interactive electronic format that uses a
IEEE/ASTM SI 10 American National Standard for Use of
special software tool, designated as prediction profilers or
theInternationalSystemofUnits(SI):TheModernMetric
profilers. This special profiler may be used to determine
System
laboratory test conditions that provide equivalent tire internal
temperatures for the tread centerline, belt edge, or ply ending
3. Terminology
region for the two operational conditions, that is, the curved
3.1 Definitions:
laboratory roadwheel and flat highway test surfaces.
3.1.1 belt edge (BE) temperature, n— in the cross section of
1.2 The prediction profilers are based on empirically devel-
a radial tire, the temperature at the edge of the stabilizer
oped linear regression models obtained from the analysis of a
(working, widest) plies or belts, for example, in the rubber
large database that was obtained from a comprehensive experi-
region of the belt edges.
mental test program for roadwheel and flat surface testing of
The boldface numbers in parentheses refer to the list of references at the end of
this standard.
1 3
This practice is under the jurisdiction ofASTM Committee F09 on Tires and is Supporting data have been filed at ASTM International Headquarters and may
the direct responsibility of Subcommittee F09.30 on Laboratory (Non-Vehicular) be obtained by requesting Research Report RR:F09-1002.
Testing. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved Oct. 1, 2016. Published October 2016. Originally contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
approved in 2010. Last previous edition approved in 2010 as F2779 – 10. DOI: Standards volume information, refer to the standard’s Document Summary page on
10.1520/F2779-10R16. the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
F2779 − 10 (2016)
3.1.2 contained air temperature, n—the temperature of the 3.1.17 tire, radial, n—a pneumatic tire in which the ply
air contained within the tire cavity when the tire is mounted cordsthatextendtothebeadsarelaidsubstantiallyat90°tothe
and inflated on the proper rim. center line of the tread, the tire being stabilized by a belt. F538
3.1.18 tire speed rating, n—the maximum speed for which
3.1.3 curved equivalent test severity, n—in tire testing, the
the use of the tire is rated under certain conditions as
test conditions (load, rotational speed, tire inflation pressure)
designated by the speed symbol marked on the tire sidewall or
on the flat or highway surface that will provide equivalent
maximum speed rating as determined by the manufacturer.
internal tire temperatures, for example, at the belt edge, to a
known set of curved 1.707-m roadwheel surface test condi-
3.1.19 tread centerline (CL) temperature, n—in the cross
tions.
section of a radial tire, the temperature under the center of the
tread region, for example, at the bottom region of the tread
3.1.4 endurance, n—of a tire, the ability of a tire to perform
rubber component.
as designed in its intended usage conditions such as load,
inflation pressure, speed, time, and environmental conditions.
3.1.20 truck-bus tire, n—atirethatisintendedforserviceon
commercial truck-bus vehicles.
3.1.5 high speed performance, n—of a tire, the rotational
speed capability of a tire to perform as designed in its intended
4. Summary of Practice
usage conditions such as load, inflation pressure, speed, time,
and environmental conditions. 4.1 This practice provides a procedure to determine
1.707-m diameter roadwheel tire test conditions (speed, load,
3.1.6 highway equivalent test severity, n—in tire testing, the
and inflation pressure) for equivalent test severity with flat
test conditions (load, rotational speed, tire inflation pressure)
surfacetestconditions.Italsoenablestheusertodeterminethe
on the 1.707-m roadwheel that will provide equivalent internal
1.707-m diameter roadwheel test conditions for a specific
tire temperatures, for example, at the belt edge, to a known set
increase or decrease in severity with respect to flat surface test
of flat or highway surface test conditions.
severity. The converse is also true for the determination of the
3.1.7 load range, n—of a truck-bus tire, a letter designation
flat surface tire test conditions for equivalent test severity with
(F, G, H, J, L, M) used to identify a given size tire with its load
a specific set of 1.707-m diameter roadwheel test conditions.
and inflation limits when used in a specific type of service.
4.2 This practice provides a prediction profiler procedure
3.1.8 maximum rated load, n—theloadcorrespondingtothe
(see Section 7 and Annex A1) to establish equivalent test
maximum tire load capacity at the rated inflation pressure in
severity between a 1.707-m diameter rotating wheel (Practice
accordance with the publications of tire and rim standards
F551) and a flat surface, by adjusting test speed, load and
current at the time of manufacture.
inflation pressure. The prediction profiler provides the ability
to identify numerous test conditions and resultant belt edge
3.1.9 measured inflation pressure, n—gage pressure of a tire
temperature differentials within the confines of this practice as
measured at a given time under ambient temperature and
described in section 7.1.
barometric pressure. F538
4.3 Equivalent test severity is defined as the set of test
3.1.10 ply ending (PE) temperature, n— in the cross section
conditions (load, speed, and tire inflation pressure) that pro-
of a radial tire, the temperature at the higher turn-up end of the
vides equivalent steady state tire belt edge (BE), tread center-
body ply, for example, in the apex component region of the
line(CL),orplyending(PE)temperaturesfor: (1)aconversion
ending.
from flat surface conditions to 1.707-m diameter roadwheel
3.1.11 rated inflation pressure, n—the minimum cold infla-
conditions, or (2) a conversion from 1.707-m diameter road-
tion pressure specified at the maximum rated load of a tire in
wheel conditions to flat surface conditions.
accordance with the publications of tire and rim standards
current at the time of manufacture.
5. Significance and Use
3.1.12 rim, n—specially shaped circular periphery to which
5.1 Historically, tires have been tested for endurance by a
a tire may be mounted with appropriate bead fitment. F538
variety of test methods. Some typical testing protocols have
3.1.13 test inflation pressure, n—specified gage pressure of
been: (1) proving grounds or highway testing over a range of
a tire mounted on a rim, measured at a given time under speeds,loads,andinflations, (2)testingonfleetsofvehiclesfor
ambient temperature and barometric pressure for evaluation
extended periods of time, and (3) indoor (laboratory) testing of
purposes. tires loaded on a rotating 1.707-m diameter roadwheel;
however, the curved surface of a 1.707-m diameter roadwheel
3.1.14 test load, n—the force applied to a tire through the
results in a significantly different tire behavior from that
rim; it is normal to the metal loading plate onto which the tire
observed on a flat or highway surface.
is loaded. F538
5.1.1 This practice addresses the need for providing equiva-
3.1.15 test speed, n—the tangential speed at the point of
lent test severity over a range of typical tire operating condi-
contact with the road or curved surface of a rotating tire for
tions between a 1.707-m diameter roadwheel surface (Practice
evaluation purposes.
F551)andaflatsurface.Therearedifferentdeformationsofthe
3.1.16 tire, pneumatic, n—a hollow tire that becomes load- tire footprint on curved versus flat surfaces resulting in
bearing upon inflation with air, or other gas, to a pressure different footprint mechanics, stress/strain cycles, and signifi-
above atmospheric. F538 cantly different internal operating temperatures for the two
F2779 − 10 (2016)
types of contact surface. Since tire internal temperatures are temperature(s),” the user will be able to identify (via the
key parameters influencing tire endurance or operating char- profilers) roadwheel test conditions to achieve the temperature
acteristics under typical use conditions, it is important to be “delta(s).” The equivalency determination is based upon a
able to calculate internal temperature differentials between “delta” in rotational speed, load, and/or inflation from the
curvedandflatsurfacesforarangeofloads,inflationpressures known highway operating conditions within the limitations
and rotational velocities (speeds). specified in 6.1.
7.1.2 The converse also applies for equivalent highway test
5.2 Data from lab and road tire temperature measurement
conditions that can be identified from specified roadwheel test
trials were combined, statistically analyzed, and tire tempera-
conditions by use of the curved-to-flat (CTF) prediction
ture prediction models derived.
profilers.
5.2.1 The fit of the models to the data is shown as the
coefficient of determination, R , for the two critical crown area
7.2 When using either the ‘FTC (or CTF) Delta DegC’ or
temperatures, i.e. tread centerline and belt edge, as well as the
the ‘FTC (or CTF) Delta % DegC’ prediction profilers, four
ply ending area:
variables are available for interactive modification:
R = 0.89, 0.90, and 0.89 respectively
“RW Delta km/h” The change in tire rotational speed for
1.7m
5.2.2 These prediction models were used to develop the the roadwheel relative to the highway
speed.
prediction profilers described in Section 7 and Annex A1.
“RW % of Flat Inf” The percent change in roadwheel tire
1.7m
6. Limitations
inflation relative to the highway tire
inflation.
6.1 The procedures within this standard are valid for com-
mercial radial pneumatic truck-bus tires of load range F
“RW % of Flat Load” The percent change in roadwheel tire
1.7m
load relative to the highway tire load.
throughloadrangeLandforthefollowingrangesoftestspeed,
tire inflation pressure and tire load, for flat test surfaces and
“Speed Rating ” The manufacturer’s recommended
km/h
1.707-m diameter roadwheels:
highway speed rating for a specific tire.
6.1.1 Tire test speed in the range of 77 to 132 km/h (flat
7.2.1 These variables appear along the x-axis of the predic-
surface) and 40 to 132 km/h (curved surface).
tion profiler and can be changed by clicking and dragging.
6.1.2 Tire test inflation pressure in the range of 58 to 107 %
Effects of changing these variables can be viewed as tempera-
of sidewall-stamped inflation pressure.
ture changes in ply ending, tread centerline, and belt edge
6.1.3 Tire test load in the range of 49 to 128 % of sidewall-
regions identified on the y-axis, depending whether the “Delta
stamped maximum load.
Deg C” or the “Delta % Deg C” prediction profiler is used:
6.1.4 Ambient temperature = 38°C.
“FTC Pred PE Delta DegC” (or “FTC Pred PE Delta % DegC”)
6.2 The procedures described in Section 7 identify equiva-
“FTC Pred CL Delta DegC” (or “FTC Pred CL Delta % DegC”)
lent operating conditions for a flat surface and a 1.707-m
diameter roadwheel by using empirical models to match tire
“FTC Pred BE Delta DegC” (or “FTC Pred BE Delta % DegC”)
internal component temperatures. These empirical models
7.3 The curved-to-flat (CTF) prediction profilers maintain
were derived from a wide variety of tires tested within the
the same labels for the y-axis while the x-axis are labeled from
above ranges and can be used to interpolate at any conditions
the perspective of identifying the required changes from
within the constraints listed above. It is not recommended that
roadwheel conditions to flat conditions in order to achieve the
theproceduresbeusedforextrapolationbeyondtheconstraints
targeted severity levels on the flat surface.
listed above.
7.4 See Annex A1 for examples of prediction profilers
7. Procedure
outputs.
7.1 Equivalent Test Severity Prediction Profilers:
7.5 Flat-to-Curved (FTC) Prediction Profiler – Macro But-
7.
...