ASTM F724-94a(2004)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.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: F724 – 94a (Reapproved 2004)
Standard Test Method for
Outdoor Evaluation of Tire Sidewall Component Cracking
Resistance
ThisstandardisissuedunderthefixeddesignationF724;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginal
adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.Asuperscript
epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope D1149 Test Methods for Rubber Deterioration—Cracking
in an Ozone Controlled Environment
1.1 This test method covers procedures for evaluating pas-
D1171 Test Method for Rubber Deterioration—Surface
senger car tires for sidewall component integrity and cracking
Ozone Cracking Outdoors or Chamber (Triangular Speci-
resistance, using an outdoor roadwheel.
mens)
1.2 This test method evaluates the resistance of tire side-
D3395 Test Methods for Rubber Deterioration—Dynamic
walls to dynamic weathering, atmospheric ozone cracking,
Ozone Cracking in a Chamber
fatigue cracking, or openings of splices within, or of junctures
F538 Terminology Relating to the Characteristics and Per-
between, sidewall components and cracking at molded side-
formance of Tires
wall elements.
1.3 This test method is useful for evaluating tire black
3. Terminology
sidewalls, white sidewalls, and coverstrips.
3.1 Definitions:
1.4 This test method is limited to comparative performance
3.1.1 black sidewall, n—a sidewall on which only black
testing between a “control” sidewall component or assembly
compounds comprise the outer visible surface of a tire.
and one or more experimental alternatives that are built onto
(F538)
the same tire (“multisection”) or onto tires that are identical in
3.1.2 clinch strip, n—high-modulus or high-hardness com-
all respects other than the sidewall variation.
pound applied between the carcass and the sidewall in the bead
1.5 This test method is not applicable to evaluation of
area to reinforce the bead. (F538)
sidewall resistance to abrasion, as may be experienced in
3.1.3 coverstrip, n—a thin layer of black compound that
severe cornering or curb scuffing.
covers the unexposed white sidewall portion of a finished tire.
1.6 The values stated in SI units are to be regarded as the
(F538)
standard.
3.1.4 crazing, n—minute, closely grouped, generally super-
1.7 This standard does not purport to address all of the
ficial cracks that usually result from light-activated oxidation.
safety concerns, if any, associated with its use. It is the
(F538)
responsibility of the user of this standard to establish appro-
3.1.5 flex cracking, v—cracking primarily caused by appli-
priate safety and health practices and determine the applica-
cation of mechanical stress-strain cycling. (F538)
bility of regulatory limitations prior to use. For specific
3.1.6 juncture, n—the interface between two different tire
precaution statements, see 5.2.
components or different compounds within the same compo-
2. Referenced Documents nent. (F538)
2 3.1.7 juncture cracking, n—a crack with opening originat-
2.1 ASTM Standards:
ing at a juncture between two components. (F538)
D518 Test Method for Rubber Deterioration—Surface
3 3.1.8 juncture opening, n—a separation developing in a
Cracking
juncture. (F538)
3.1.9 rim strip, n—a layer of compound, with or without
This test method is under the jurisdiction of ASTM Committee F09 on Tires
fabric reinforcement, that is applied at the bead to protect the
and is the direct responsibility of Subcommittee F09.30 on Laboratory (Non-
carcasspliesagainstdamagefrommountingtoolsandfromrim
Vehicular) Testing.
chafing during service. (F538)
Current edition approved Dec. 1, 2004. Published December 2004. Originally
approved in 1981. Last previous edition approved in 2000 as F724 – 94a (2000).
DOI: 10.1520/F0724-94AR04.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website.
Withdrawn. The last approved version of this historical standard is referenced
on www.astm.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
F724 – 94a (2004)
3.1.10 sidewall, n—of a tire, that portion of a tire between 5.1.4 System for determining accumulated cycles of rota-
the tread and the bead. (F538) tion of each test tire.
3.1.11 sidewall component, n—an individual part of the 5.2 Safety Precautions:
sidewall construction, either a separate compound or a sepa- 5.2.1 The apparatus shall be surrounded by a suitable
rately assembled piece. (F538) enclosure to trap tire fragments in the event of a catastrophic
3.1.12 sidewall rubber, n—theexteriorrubberlayerofatire failure during the test.
that extends over the sidewall part of the carcass. (F538) 5.2.2 The controls for the apparatus shall be situated outside
3.1.13 splice, n—the joint formed either by overlapping or the enclosure.
butting the ends of a given tire component in the course of
6. Sampling
assembling the tire. (F538)
3.1.14 splice crack, n—a crack originating at a splice.
6.1 Asampling plan is not applicable since this test method
(F538)
is intended for research and development testing only. Test
3.1.15 splice opening, n—a parting of a splice along the
specimens (see Section 7) shall be tested simultaneously with
interface of the assembled ends of a given component.
a control specimen for direct comparison of relative perfor-
(F538)
mance.
3.1.16 veneer, n—athinlayerofrubbercoveringthesurface
of the tire sidewall. (F538) 7. Test Specimens
3.1.17 weather cracking, n—distinct surface cracks induced
7.1 A test specimen shall be a given assembly of sidewall
by action of ozone in those areas of sidewall that are under
components, specific as to component formulations, assembly
tension; the cracks usually form perpendicularly to the direc-
cross-section geometry, and preparation procedure. The test
tion of stress.
specimen may cover the entire sidewall circumference of the
3.1.18 white sidewall, n—a sidewall that contains a white
test tire and be compared with a control tire or it may cover a
(or light-colored) compound as a part of the total sidewall.
section of the sidewall and be compared with a control section
(F538)
and other test specimen sections built onto the same (multi-
section) tire.
4. Significance and Use 1
7.2 Atest specimen section shall cover ⁄4 of the circumfer-
ence of the tire sidewall.
4.1 Test Methods D518, D1149, D1171, and D3395 can be
used to evaluate different aspects of fatigue and weather 7.3 In multisection tire tests, only specimens on the same
side of the tire shall be compared directly.
cracking resistance of sidewall component materials in the
form of test specimens. The present method applies to com-
8. Selection and Preparation of Test Tires
plete tires that are subjected to actual weather exposure
conditions. The present method is satisfactory for research and
8.1 All test tires shall be approximately the same age and
development purposes but is not applicable to regulatory
subjected to the same pretest conditions, particularly as related
statutes or purchase specifications until standard classifications
to heat and ultraviolet exposure.
ofstateofcracking,similartothoseinTestMethodD1171,can
8.2 Multisection test tires shall have been prepared with the
be established.
test components (for example, varied compounds) having the
same cross-sectional profile and dimensions, so as to avoid
5. Apparatus
extraneous mechanical stress variability between the compo-
nents, unless the profile variation is a test variable.
5.1 Outdoor Roadwheel—An apparatus situated outdoors
8.3 The test component surfaces of tires shall be washed
and consisting of:
with water to remove any temporary protective coating but
5.1.1 One or more smooth steel road wheels of specified
shall not be subjected to solvent or other surface treatment (in
diameter. The road wheel(s) shall be wide enough to extend
the process of mounting, etc.) that may affect performance
beyond the test tire foot print width. The road wheel diameter
unless this is a part of the experimental study.
shall be no less than 610 mm (24 in.). Smaller diameter wheels
may produce excessive flexing and premature extraneous tire
9. Procedure
failure.
5.1.2 Satellite stations for loading several test tires against 9.1 Mount a test tire on a rim contour approved by the Tire
the road wheel with known constant force. and Rim Association for its particular size. For tire-to-tire
5.1.2.1 Each satellite station can individually unload and comparative tests, rims shall be of the same width.
withdraw the tire from contact with the road wheel in the event 9.2 Mount the tire with the valve at a convenient reference
of an inflation pressure loss or other potentially catastrophic pointfordescribingthelocationsofcracksorotherdegradation
occurrence. as they occur.
9.3 Inflate the tire to the selected test pressure at ambient
5.1.2.2 The tire-loading system may be done by any system
that provides a constant force to maintain the desired tire temperature. A commonly used inflation pressure is 138 kPa
deflection throughout the test.
5.1.3 Adrive motor that can drive the road wheel(s), within
61 %
...