ASTM F1112-06a(2010)
(Test Method)Standard Test Method for Static Testing of Tubeless Pneumatic Tires for Rate of Loss of Inflation Pressure
Standard Test Method for Static Testing of Tubeless Pneumatic Tires for Rate of Loss of Inflation Pressure
SIGNIFICANCE AND USE
Inflation pressure retention is an important property of tire performance because underinflation can adversely affect tire rolling resistance, handling, structural integrity, and tread life.
This test method is useful for research and development evaluation of the effects of tire component formulations and geometry on inflation pressure retention. Testing for rate of pressure loss under static conditions is practical because of the following:
Tires in normal use are predominantly at rest, and
Relative air diffusion rates of various tires in normal intermittent road service will correlate with static relative rates, to a first approximation. The relative air diffusion rates of different tires may not be quite the same under dynamic flexing as when tested statically, but the difference is believed to be small.
The results from this test method are not suitable for inferring tire inflation retention under severe service conditions, such as heavy cornering or impacts, that might cause significant air loss at the tire-rim seal.
SCOPE
1.1 This test method covers the determination of the rate of inflation pressure loss resulting from air diffusion through the structures of tubeless tires under constant temperature conditions. The testing is done under static conditions, that is, nonrotating, nonloaded tires.
1.2 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.
1.3 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.
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Standards Content (Sample)
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Designation:F1112 −06a (Reapproved 2010)
Standard Test Method for
Static Testing of Tubeless Pneumatic Tires for Rate of Loss
of Inflation Pressure
This standard is issued under the fixed designation F1112; 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 3.1.3 normalized inflation pressure, n— measured pressure
ofatireadjusted,accordingtotheidealgaslaw,tothenominal
1.1 This test method covers the determination of the rate of
test temperature and one atmosphere external barometric
inflation pressure loss resulting from air diffusion through the
pressure. F538
structures of tubeless tires under constant temperature condi-
tions. The testing is done under static conditions, that is,
4. Summary of Test Method
nonrotating, nonloaded tires.
4.1 Test tires are mounted on rims, fitted with calibrated
1.2 The values stated in SI units are to be regarded as the
precision pressure measuring devices, inflated to the desired
standard. The values given in parentheses are for information
pressure, and, after a period of stabilization, are monitored for
only.
inflation pressure as a function of time under static, constant
1.3 This standard does not purport to address all of the
temperature conditions.
safety concerns, if any, associated with its use. It is the
4.2 Measured inflation pressures are normalized to the
responsibility of the user of this standard to establish appro-
nominal test temperature and one atmosphere barometric
priate safety and health practices and determine the applica-
pressure for calculation of pressure loss rates.
bility of regulatory limitations prior to use.
4.3 Two or more tires per tire specification are tested for
pressure loss rate over a period of two to six months. High
2. Referenced Documents
precision in the equipment and data may allow shortening the
2.1 ASTM Standards:
test. See 9.6, 10.5, and Section 12.
D4483Practice for Evaluating Precision for Test Method
4.4 The pressure loss rate is calculated as percent loss per
StandardsintheRubberandCarbonBlackManufacturing
month at the nominal test temperature and one atmosphere
Industries
barometric pressure (101.3 kPa).
F538Terminology Relating to the Characteristics and Per-
formance of Tires
5. Significance and Use
3. Terminology
5.1 Inflation pressure retention is an important property of
tire performance because underinflation can adversely affect
3.1 Definitions:
tire rolling resistance, handling, structural integrity, and tread
3.1.1 inflation pressure loss rate, n—rate of change of
life.
normalizedinflationpressure,determinedfromtheslopeofthe
linear portion of the log pressure versus time curve. F538
5.2 Thistestmethodisusefulforresearchanddevelopment
evaluation of the effects of tire component formulations and
3.1.2 measured inflation pressure, n—gauge pressure of a
geometry on inflation pressure retention. Testing for rate of
tire measured at a given time under ambient temperature and
pressure loss under static conditions is practical because of the
barometric pressure. F538
following:
5.2.1 Tires in normal use are predominantly at rest, and
5.2.2 Relative air diffusion rates of various tires in normal
This test method is under the jurisdiction of ASTM Committee F09 on Tires
intermittentroadservicewillcorrelatewithstaticrelativerates,
and is the direct responsibility of Subcommittee F09.30 on Laboratory (Non-
Vehicular) Testing.
to a first approximation. The relative air diffusion rates of
Current edition approved Dec. 1, 2010. Published March 2011. Originally
differenttiresmaynotbequitethesameunderdynamicflexing
approved in 1987. Last previous edition approved in 2006 as F1112–06a. DOI:
as when tested statically, but the difference is believed to be
10.1520/F1112-06AR10.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or small.
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
5.3 The results from this test method are not suitable for
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. inferring tire inflation retention under severe service
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
F1112−06a (2010)
conditions, such as heavy cornering or impacts, that might 7.9 A sealing tape such as TFE-fluorocarbon or a room-
cause significant air loss at the tire-rim seal. temperature curable sealant shall be used on all threaded
connections in the valve-adapter-gauge/transducer assembly.
6. Interferences
7.10 Apressure-measuring device shall be connected to the
adapter (or valve) to continuously measure inflation pressure.
6.1 Ambient temperature excursions greater than 63°C
(65°F) for several hours may significantly alter both the air The device shall have a resolution of at least 2 kPa (0.25 psi)
and an accuracy of 61% of the measured pressure. Devices
diffusion rate through the tire and the driving force inflation
pressure, thereby causing variability in the rate of tire pressure shall be calibrated before and after each use with a reference
device whose calibration is traceable to the National Institute
loss. Some temperature variations can result from inconsistent
air currents around the test tires, or from spatial temperature of Standards and Technology (NIST). The pressure-measuring
device must maintain this accuracy over the duration of the
gradients in static air spaces. The effects can be significant
where heat-generating tests such as laboratory road wheels are test. Quality Bourdon tube gauges have been satisfactory for
180-day duration tests. Electronic pressure transducers and
operating intermittently in the same room.
data acquisition systems are advantageous due to their
6.2 Other causes for inconsistent results are minute leaks in
accuracy, repeatability, and continuous remote monitoring
the tire, rim, valve, or pressure measuring device assembly; as
capability. To ensure their accuracy, these systems must be
well as varied service or other heat history of the test tires.
calibrated as a single, functional unit; transducer, cabling,
signal conditioner, and data acquisition device.These systems,
7. Sampling and Preparation of Test Tires
along with stable environmental conditions, can enable shorter
7.1 All of the tires in a sample should have the desired
duration tests producing results comparable to 180-day test
producingplantanddatecodesandsimilarstorageandservice
results.
temperature history.
7.11 Inflatethetire-rimassemblyoutfittedwiththepressure
7.2 Tires must be free of molding or other defects, particu-
gauge or transducer to the desired starting pressure. Test for
larly on the bead area and innerliner surfaces.
leaksbysubmersioninawatertank,uptothebaseofthegauge
or transducer, for at least 30 min or carefully check both beads
7.3 New tires should be used for evaluation of construction
and fittings for leaks with leak detection fluid. If other than a
or compound variations.
painted steel rim is used, the entire rim must be checked for
7.4 Minimum recommended sample size is two tires for
leaks.
each type of tire or treatment being tested.
7.12 Afterconfirmingthatthetire-rimassemblyisfreefrom
7.5 Test tires are to be mounted on rims of the proper bead
leaks, fit the valve or adapter opening with a sealing cap, and
seat diameter with clean, smooth surfaces in the bead seat
keep the tire in the same orientation to avoid causing new
areas,particularlyinthevicinityoftheweld.Rimflangesmust
leaks.
be free of sharp edges or scuffs that could damage the tire
7.13 After the leakage check, condition the tires at the test
during mounting. Bead seat diameters must be verified using a
room temperature for 48 h; then adjust to the starting test
certifieddisctape(a.k.a.balltape)andbeacceptableaccording
pressure. Replace the sealing cap on the valve or adapter. If a
to an applicable standard such as the Tire & RimAssociation,
pressure drop of more than 3 kPa (0.5 psi) occurs over the
Inc.(T&RA).Paintedsteelisthematerialofchoiceforthetest
conditioning period, recheck the assembly for leakage accord-
rims due to the low permeation rates. If another rim material
ing to 7.11 and, if necessary, dismount and remount the tire.
mustbeused,thenprecautionsaretobetakentoinsureagainst
Greaterthan48hconditioningmaybenecessaryforsometires
air permeation through the rim material.
suchashigh-pressurecompactspares,whosegrowthcanaffect
7.6 Acommercial bead-rim lubricant shall be applied to the
early inflation loss results.
tire bead areas and rim before mounting. Vegetable oil or
soap-based lubricants are recommended.
8. Test Chamber
7.7 Mount the tire on the rim according to the practice
8.1 The test chamber shall be controlled to provide a mean
recommended by Rubber ManufacturersAssociation (RMA).
ambient temperature that is within 60.6°C (61°F) of the
Do not exceed 275 kPa (40 psi) inflation pressure for seating
nominal test temperature and with overall variation within
beads. Use of sealants in the bead-flange area should be
63°C (65°F) over the course of the test.
avoided since it can prevent proper seating.
8.2 Nominal test temperatures currently in use are: 21, 24,
7.8 The rim shall be outfitted with either two serviceable
30, and 38°C (70, 75, 86, and 100°F).
valves or a single valve to which is then attached a metal “T”
8.3 Air in the test chamber should be forcibly circulated to
adapter that permits permanent attachment of a pressure-
minimize spatial temperature gradients.
measuring device (gauge/transducer) to one opening and infla-
tion through the other.
9. Procedure
9.1 Placethetesttiresinthetestchambersoastoallowfree
air circulation around them and easy visual access to the
Available from Rubber Manufacturers Association, 1400 K. St. N.W.,
Washington, DC20005. pressure gauges. The tires shall not be moved during the test.
F1112−06a (2010)
9.2 Record inflation pressures, concurrent ambient Thus, pressure loss in absolute units will vary as the actual
temperatures, and barometric pressures frequently (daily read- nominal pressure changes, but a loss rate can be expressed by
ings are recommended) for two weeks. If using a pressure the constant, β.
gauge,tapthegaugelightlypriortoeachreading.Tiresshallbe
10.4 The calculated loss rate constant, β, will be in units of
considered to be satisfactorily conditioned when the slope of
1/day.This number will typically be a very small decimal; it is
the logarithm of the normalized inflation pressure versus time
convenient, and perhaps more intuitively meaningful, to ex-
relationship becomes constant.
press loss rate as a percent per month. This is done by
9.3 The test shall be continued if replicate tires agree with multiplying β by 3000 (which is 100%×30 days/month).
eachotherwithin6kPa(approximately1psi)inflationpressure
10.5 Calculationsofsteadystatelossrateandpredictionsof
after two weeks. Otherwise, recheck the suspect assembly for
futurepressurescanbemadefromanypointinthetest(beyond
leaks according to 7.11, and restart the test.
the first 30 days as explained in X1.3). The accuracy of such
9.4 Inflation pressure readings and concurrent ambient tem- predictions will depend on the appropriateness of the model as
perature and barometric pressure readings shall be recorded at well as the precision level of data obtained that, in turn, will
least once per week during the remaining test period. Continu- depend on factors such as the following:
ous monitoring of ambient temperature is desirable to ensure 10.5.1 Care in reading pressure gauges,
that the tire is at equilibrium temperature when its pressure is 10.5.2 Resolution and accuracy of pressure measuring
measured. devices,
10.5.3 Maintenance of a relatively constant temperature,
9.5 Correct inflation pressure readings, P , to the nominal
and
test temperature and one atmosphere barometric pressure
10.5.4 Frequency of pressure measurements.
(101.3 kPa, 14.69 psi) by using the equation in 10.1.
9.6 A commonly used test duration is 180 days. The test
11. Report
period may be shorter or longer depending on the precision
11.1 For each test tire, report the loss rate as a percent per
level of the data. More frequent or continuous electronic
month (β×3000) and other pertinent test parameters includ-
measurements are recommended if shorter term projections of
ing:
performance are intended. See also 4.3.
11.1.1 Total test duration in days,
10. Calculation 11.1.2 Projected inflation pressure, if applicable,
11.1.3 Average ambient temperature and range over test,
10.1 Calculate normalized pressures from the formula:
11.1.4 Initial inflation pressure,
P 5 ~P 1B !~T /T ! 2 B (1)
1 1 2 1 2
11.1.5 Actual and “best fit” final inflation pressure, and
11.1.6 Starting date.
where:
P = normalized inflation pressure, kPa, 11.2 Alsoreportthemanufacturer,line,size,andU.S.Dept.
P = measured inflation pressure, kPa,
of Transportation (DOT) serial number for each tire.
B = measured barometric pressure, kPa
11.3 AnexampletreatmentoftestdataisgiveninAppendix
B = reference barometric pressure, kPa (one atmo-
X1.
sphere=101.3 kPa),
T = measured temperature, °K, and
12. Precision and Bias
T = nominal test temperature, °K.
NOTE 1—Temperature in Kelvin equals Celsius plus 273.15. 12.1 The precision and bias section has been prepared in
accordance with Practice D4483. Refer to this for terminology
10.2 Air permeation data fits the model of the following
and other statistical calculation details.
form:
βt 12.2 An interlaboratory test was conducted in 1985 using a
P 5 P e (2)
o
set of used uniform tire quality grading (UTQG) Course
where:
MonitoringTires(CMT).Thissetoftentireswasfurnishedby
P = normalized pressure, kPa, one of the participating laboratories.
P = normalized initial pressure, kPa,
o
12.3 Five laboratories participated in the interlaboratory
β = loss rate per day at the nominal test temperature, and
test. Each laboratory tested two tires following the test proce-
t = test time, days.
dure as outlined in this test method. Thus, there are only 5
10.3 Aleast squares fit can be obtained after transformation
degrees of freedom (df) for repeatability (r) and four df for
of the model equation to the following form:
reproducibility (R). These low df for r and R are not optimum
for a good reliable estimate of overall precision.
lnP 5 α1βt (3)
12.4 The tire air pressure loss rate was measured simulta-
where:
neouslyforeachofthetwotires(perlaboratory)at22 60.8°C.
α =ln P
o
This loss rate, as specified by this test method, is
...
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