1、Designation: F2779 10 (Reapproved 2016)Standard Practice forCommercial Radial Truck-Bus Tires to Establish EquivalentTest Severity Between a 1.707-m (67.23-in.) DiameterRoadwheel and a Flat Surface1This standard is issued under the fixed designation F2779; the number immediately following the design
2、ation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This practice describes the proc
3、edure to identify equiva-lent test severity conditions between a 1.707-m diameterlaboratory roadwheel surface and a flat or highway surface forcommercial radial truck-bus tires.1.1.1 Tire operational severity, as defined as the running oroperational temperature for certain specified internal tireloc
4、ations, is not the same for these two test conditions. It istypically higher for the laboratory roadwheel at equal load,speed and inflation pressure conditions due to the curvatureeffect.1.1.2 The practice applies to specific operating conditions ofload range F through L for such commercial radial t
5、ruck-bustires.1.1.3 The specific operating conditions under which theprocedures of the practice are valid and useful are completelyoutlined in Section 6 (Limitations) of this standard.1.1.4 It is important to note that this standard is composed oftwo distinct formats:1.1.4.1 The usual text format as
6、 published in this volume ofthe Book of Standards (Vol 09.02).1.1.4.2 A special interactive electronic format that uses aspecial software tool, designated as prediction profilers orprofilers. This special profiler may be used to determinelaboratory test conditions that provide equivalent tire intern
7、altemperatures for the tread centerline, belt edge, or ply endingregion for the two operational conditions, that is, the curvedlaboratory roadwheel and flat highway test surfaces.1.2 The prediction profilers are based on empirically devel-oped linear regression models obtained from the analysis of a
8、large database that was obtained from a comprehensive experi-mental test program for roadwheel and flat surface testing oftypical commercial truck and bus tires. See Section 7 andReferences (1, 2)2,3for more details.1.2.1 For users viewing the standard on CD-ROM or PDF,with an active and working int
9、ernet connection, the profilerscan be accessed on the ASTM website by clicking on the linksin 7.5 and 7.6.1.2.2 For users viewing the standard in a printed format, theprofilers can be accessed by entering the links to the ASTMwebsite in 7.5 and 7.6 into their internet browsers.1.3 For this standard,
10、 SI units shall be used, except whereindicated.1.4 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regu
11、latory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:4F538 Terminology Relating to the Characteristics and Per-formance of TiresF551 Practice for Using a 67.23-in. (1.707-m) DiameterLaboratory Test Roadwheel in Testing TiresIEEE/ASTM SI 10 American National Standard for Use ofth
12、e International System of Units (SI): The Modern MetricSystem3. Terminology3.1 Definitions:3.1.1 belt edge (BE) temperature, n in the cross section ofa radial tire, the temperature at the edge of the stabilizer(working, widest) plies or belts, for example, in the rubberregion of the belt edges.1This
13、 practice is under the jurisdiction of ASTM Committee F09 on Tires and isthe direct responsibility of Subcommittee F09.30 on Laboratory (Non-Vehicular)Testing.Current edition approved Oct. 1, 2016. Published October 2016. Originallyapproved in 2010. Last previous edition approved in 2010 as F2779 10
14、. DOI:10.1520/F2779-10R16.2The boldface numbers in parentheses refer to the list of references at the end ofthis standard.3Supporting data have been filed at ASTM International Headquarters and maybe obtained by requesting Research Report RR:F09-1002.4For referenced ASTM standards, visit the ASTM we
15、bsite, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United Sta
16、tes13.1.2 contained air temperature, nthe temperature of theair contained within the tire cavity when the tire is mountedand inflated on the proper rim.3.1.3 curved equivalent test severity, nin tire testing, thetest conditions (load, rotational speed, tire inflation pressure)on the flat or highway
17、surface that will provide equivalentinternal tire temperatures, for example, at the belt edge, to aknown set of curved 1.707-m roadwheel surface test condi-tions.3.1.4 endurance, nof a tire, the ability of a tire to performas designed in its intended usage conditions such as load,inflation pressure,
18、 speed, time, and environmental conditions.3.1.5 high speed performance, nof a tire, the rotationalspeed capability of a tire to perform as designed in its intendedusage conditions such as load, inflation pressure, speed, time,and environmental conditions.3.1.6 highway equivalent test severity, nin
19、tire testing, thetest conditions (load, rotational speed, tire inflation pressure)on the 1.707-m roadwheel that will provide equivalent internaltire temperatures, for example, at the belt edge, to a known setof flat or highway surface test conditions.3.1.7 load range, nof a truck-bus tire, a letter
20、designation(F, G, H, J, L, M) used to identify a given size tire with its loadand inflation limits when used in a specific type of service.3.1.8 maximum rated load, nthe load corresponding to themaximum tire load capacity at the rated inflation pressure inaccordance with the publications of tire and
21、 rim standardscurrent at the time of manufacture.3.1.9 measured inflation pressure, ngage pressure of a tiremeasured at a given time under ambient temperature andbarometric pressure. F5383.1.10 ply ending (PE) temperature, n in the cross sectionof a radial tire, the temperature at the higher turn-up
22、 end of thebody ply, for example, in the apex component region of theending.3.1.11 rated inflation pressure, nthe minimum cold infla-tion pressure specified at the maximum rated load of a tire inaccordance with the publications of tire and rim standardscurrent at the time of manufacture.3.1.12 rim,
23、nspecially shaped circular periphery to whicha tire may be mounted with appropriate bead fitment. F5383.1.13 test inflation pressure, nspecified gage pressure ofa tire mounted on a rim, measured at a given time underambient temperature and barometric pressure for evaluationpurposes.3.1.14 test load,
24、 nthe force applied to a tire through therim; it is normal to the metal loading plate onto which the tireis loaded. F5383.1.15 test speed, nthe tangential speed at the point ofcontact with the road or curved surface of a rotating tire forevaluation purposes.3.1.16 tire, pneumatic, na hollow tire tha
25、t becomes load-bearing upon inflation with air, or other gas, to a pressureabove atmospheric. F5383.1.17 tire, radial, na pneumatic tire in which the plycords that extend to the beads are laid substantially at 90 to thecenter line of the tread, the tire being stabilized by a belt. F5383.1.18 tire sp
26、eed rating, nthe maximum speed for whichthe use of the tire is rated under certain conditions asdesignated by the speed symbol marked on the tire sidewall ormaximum speed rating as determined by the manufacturer.3.1.19 tread centerline (CL) temperature, nin the crosssection of a radial tire, the tem
27、perature under the center of thetread region, for example, at the bottom region of the treadrubber component.3.1.20 truck-bus tire, na tire that is intended for service oncommercial truck-bus vehicles.4. Summary of Practice4.1 This practice provides a procedure to determine1.707-m diameter roadwheel
28、 tire test conditions (speed, load,and inflation pressure) for equivalent test severity with flatsurface test conditions. It also enables the user to determine the1.707-m diameter roadwheel test conditions for a specificincrease or decrease in severity with respect to flat surface testseverity. The
29、converse is also true for the determination of theflat surface tire test conditions for equivalent test severity witha specific set of 1.707-m diameter roadwheel test conditions.4.2 This practice provides a prediction profiler procedure(see Section 7 and Annex A1) to establish equivalent testseverit
30、y between a 1.707-m diameter rotating wheel (PracticeF551) and a flat surface, by adjusting test speed, load andinflation pressure. The prediction profiler provides the abilityto identify numerous test conditions and resultant belt edgetemperature differentials within the confines of this practice a
31、sdescribed in section 7.1.4.3 Equivalent test severity is defined as the set of testconditions (load, speed, and tire inflation pressure) that pro-vides equivalent steady state tire belt edge (BE), tread center-line (CL), or ply ending (PE) temperatures for: (1) a conversionfrom flat surface conditi
32、ons to 1.707-m diameter roadwheelconditions, or (2) a conversion from 1.707-m diameter road-wheel conditions to flat surface conditions.35. Significance and Use5.1 Historically, tires have been tested for endurance by avariety of test methods. Some typical testing protocols havebeen: (1) proving gro
33、unds or highway testing over a range ofspeeds, loads, and inflations, (2) testing on fleets of vehicles forextended periods of time, and (3) indoor (laboratory) testing oftires loaded on a rotating 1.707-m diameter roadwheel;however, the curved surface of a 1.707-m diameter roadwheelresults in a sig
34、nificantly different tire behavior from thatobserved on a flat or highway surface.5.1.1 This practice addresses the need for providing equiva-lent test severity over a range of typical tire operating condi-tions between a 1.707-m diameter roadwheel surface (PracticeF551) and a flat surface. There ar
35、e different deformations of thetire footprint on curved versus flat surfaces resulting indifferent footprint mechanics, stress/strain cycles, and signifi-cantly different internal operating temperatures for the twoF2779 10 (2016)2types of contact surface. Since tire internal temperatures arekey para
36、meters influencing tire endurance or operating char-acteristics under typical use conditions, it is important to beable to calculate internal temperature differentials betweencurved and flat surfaces for a range of loads, inflation pressuresand rotational velocities (speeds).5.2 Data from lab and ro
37、ad tire temperature measurementtrials were combined, statistically analyzed, and tire tempera-ture prediction models derived.35.2.1 The fit of the models to the data is shown as thecoefficient of determination, R2, for the two critical crown areatemperatures, i.e. tread centerline and belt edge, as
38、well as theply ending area:R2= 0.89, 0.90, and 0.89 respectively5.2.2 These prediction models were used to develop theprediction profilers described in Section 7 and Annex A1.6. Limitations6.1 The procedures within this standard are valid for com-mercial radial pneumatic truck-bus tires of load rang
39、e Fthrough load range Land for the following ranges of test speed,tire inflation pressure and tire load, for flat test surfaces and1.707-m diameter roadwheels:6.1.1 Tire test speed in the range of 77 to 132 km/h (flatsurface) and 40 to 132 km/h (curved surface).6.1.2 Tire test inflation pressure in
40、the range of 58 to 107 %of sidewall-stamped inflation pressure.6.1.3 Tire test load in the range of 49 to 128 % of sidewall-stamped maximum load.6.1.4 Ambient temperature = 38C.6.2 The procedures described in Section 7 identify equiva-lent operating conditions for a flat surface and a 1.707-mdiamete
41、r roadwheel by using empirical models to match tireinternal component temperatures. These empirical modelswere derived from a wide variety of tires tested within theabove ranges and can be used to interpolate at any conditionswithin the constraints listed above. It is not recommended thatthe procedu
42、res be used for extrapolation beyond the constraintslisted above.7. Procedure7.1 Equivalent Test Severity Prediction Profilers:7.1.1 The flat-to-curved (FTC) prediction profilers are SASJMPinteractive displays based on algorithms developed fromlaboratory and highway tire temperature measurements. Th
43、eyprovide 1.707-m diameter roadwheel tire test (rotational)speed, tire test load, and tire test inflation pressure conditionsfor equivalent test severity (as well as for lesser or more severetest severity) based upon the belt edge, tread centerline, or plyending region temperatures. Before using the
44、 profilers, the userwill have targeted a roadwheel “delta temperature” amount indegrees C (or % degrees C) for one (or more) of these regionswith respect to the temperatures in these regions for the tirerunning on a flat surface, that is, the targeted operatingdifference in temperature between the r
45、oadwheel and highwaycondition. By first identifying the desired “deltatemperature(s),” the user will be able to identify (via theprofilers) roadwheel test conditions to achieve the temperature“delta(s).” The equivalency determination is based upon a“delta” in rotational speed, load, and/or inflation
46、 from theknown highway operating conditions within the limitationsspecified in 6.1.7.1.2 The converse also applies for equivalent highway testconditions that can be identified from specified roadwheel testconditions by use of the curved-to-flat (CTF) predictionprofilers.7.2 When using either the FTC
47、 (or CTF) Delta DegC orthe FTC (or CTF) Delta % DegC prediction profilers, fourvariables are available for interactive modification:“RW1.7mDelta km/h” The change in tire rotational speed forthe roadwheel relative to the highwayspeed.“RW1.7m% of Flat Inf” The percent change in roadwheel tireinflation
48、 relative to the highway tireinflation.“RW1.7m% of Flat Load” The percent change in roadwheel tireload relative to the highway tire load.“Speed Ratingkm/h” The manufacturers recommendedhighway speed rating for a specific tire.7.2.1 These variables appear along the x-axis of the predic-tion profiler
49、and can be changed by clicking and dragging.Effects of changing these variables can be viewed as tempera-ture changes in ply ending, tread centerline, and belt edgeregions identified on the y-axis, depending whether the “DeltaDeg C” or the “Delta % Deg C” prediction profiler is used:“FTC Pred PE Delta DegC” (or “FTC Pred PE Delta % DegC”)“FTC Pred CL Delta DegC” (or “FTC Pred CL Delta % DegC”)“FTC Pred BE Delta DegC” (or “FTC Pred BE Delta % DegC”)7.3 The curved-to-flat (CTF) prediction profilers maintainthe same labels for the y-axis while the x-axis are
