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IS 15731 (2006): Automotive tyres - Selection and
inspection of retreadable tyre casing [TED 7: Automotive
Tyres, Tubes and Rims]
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IS15731:2006
m+mF7%-
mm–ws-m-wmJmTwTa-TfMkFJT
Indian Standard
AUTOMOTIVE TYRES — SELECTION AND
INSPECTION OF RETREADABLE TYRE CASING
ICS 83.160.10
0 BIS 2006
BUREAU OF INDIAN STANDARDS
MANAK BHAVAN, 9 BAHADUR SHAH ZAFAR MARG
NEW DELHI 110002
December 2006 Price Group 2
Automotive Tyres,Tubes and Rims Sectional Committee, TED 7
FOREWORD
ThisIndianStandard wasadopted bytheBureau ofIndian Standards, afterthedrai-1finalized bytheAutomotive Tyres,
TubesandRims Sectional Committee had been approved bytheTransport Engineering Division Council.
Forthepurpose ofdeciding whether aparticular requirement ofthisstandard iscomplied with,thefinalvalue,observed
orcalculated, expressing theresult ofatest or analysis shallbe rounded off inaccordance with IS2: 1960‘Rulesfor
rounding offnumerical values (mvisea’. Thenumber ofsignificant places retained intherounded offvalueshouldbe
the sameasthat ofthe specified value inthis standard.
IS 15731:2006
Indian Standard
AUTOMOTIVE TYRES — SELECTION AND
INSPECTION OF RETREADABLE TYRE CASING
1 SCOPE 3.8 Cracking — Splitting inthe tread grooves.
This standard prescribes the selection criteria and
3.9 Cracks — A parting with in the rubber tread that
inspectionmethodsofretreadable tyrecasing,sothateach
does not extend to or through the cord material.
casingthatpassestheselectionandinspectionprocessshall
be acceptable for the process ofretreading.
3.10 Creep — Slow change inthe strain.
2 REFERENCE
3.11 Delamination —Asmoothseparationbetweenlayers
Thefollowingstandardcontainsprovisions,whichthrough
ofmaterial.
referenceinthistext,constituteprovisionsofthisstandard.
Atthetimeofpublication theedition indicated wasvalid.
3.12 Deflation — The distortion oftyre tlom itsnormal
All standards are subject to revision and parties to
shape.
agreements based on this standard is encouraged to
investigate the possibility of applying the most recent
3.13 Carcass — Structure orskeleton oftyre.
edition ofthe standard indicated below:
3.14 Green ~re — Abuilt tyre (new or retreadable)
[sNo. i’We
before being cured.
3400 (Part 1): Methods oftestforvulcanized rubbers:
1987 Part 1 Tensile stress/strain properties 3.15 Groove Cracking — Cracking which occurs atthe
(second revision) bottom oftread groove.
3.16 Injury (Injuries) — Any damage caused by the
3 TERMSANDDEFINITIONS
penetrating object or severe scuff or impact.
Forthepurpose ofthisstandard, thefollowing definitions
shallapply. 3.17 Injury Size—The widest opening inthecordbody
after skiving and bufllng.
3.1 Casing — Casing isaworn tyre comprising carcass
andremaining retread and sidewall material. 3.18 Nail Hole — A small puncture through a tyre
made by asharp object such asanail or screw.
3.2 Retreadable Casing — The casing suitable for
retreading after inspection. 3.19 Open Splice — A defect caused by failure of the
rubber toknittogether properly atthe splice during cure.
3.3 Casing Distortion — Aprocessing defect inwhich
the natural shape of the tyre isdeformed by constriction 3.20 Overloading —Tye overloading canbedangerous
inthematrix during the retreading process.
and is not recommended. However, note that tyre load
capacity can be increased in certain cases by increased
3.4 Corrosion — Degradation of steel reinforcement in inflation or control to lower speeds.
thetyre.
3.21 Ozone — Aform of oxygen that accelerates aging
3.5 Chunking —Breaking awayofpiecesofrubberfrom
andweathering intyres.
thetread.
3.22 Ozone Checking —Theformation offinecracksin
3.6 Circumferential Breaks — A tyre injury running arubber surface dueto ozone inthe environment.
parallel tothe bead.
3.23 Penetration —Darnagetoatyre causedbyapiercing
3.7 Circumferential Crack — Cracks inatyre running object not completely going through acasing.
parallel to the beads. Usually consists of cracks in the
tread grooves. 3.24 ply — Layer ofrubber coated parallel cords.
1
1S15731:2006
3.25 Ply Separation — Parting of rubber compound 3.42 Tread Separation — Pulling away of tread from
between adjacent plies. thetyre casing.
3.26 Porosity — Tiny air pockets in the rubber caused 3.43 Tread Tearing — Tearing awayofaportion ofthe
bypoor mould fit,insufilcient rubber, or lackofpressure. tread design.
3.27 Puncture Repair —An off-the-wheel repair ofany 3.44 Turn-Up — Part of the body ply that wraps under
injury caused byapenetrating object. The type ofrepair thebead bundle and ends inthetyre sidewall.
isdetermined bythe size and depth ofthe injury.
3.45 Weather Checking — Fine cracks in the tyre
3.28 Radial Cracking — Cracking, usually in or near sidewallsurfacecausedbyoxidationandotheratmosphere
the sidewall area, resulting from the under inflation effects.
(Cracks areperpendicular to the bead).
4 TEST METHODS
3.29 Ream —Cleananyinjury orholeprior torepairing.
4.1 T~es are to be inspected on amechanical spreader.
3.30 Retread Separation —Tread detachment fromthe These spreaders allow the inspector to visually examine
tyreatthe interface ofthe new tread andbuffed surface. eachtyreinternallyandexternally fordefectsanddamage.
3.31 Retreadability — Ability of the tyre casing to be 4.1.1 Inaddition to properly functioning tyre spreaders,
retreaded andprovide acceptable performance. adequate lighting isnecessary. The tyre inspection area,
ingeneral, shallbewelllighted.Theplacewheretyresare
3.32 Retreaded Tyre —A casingtowithanew treadhas being inspected should have internal lighting of not less
been atlixed to extend the usable lifeofthetyre. than 200 foot-candles, The recommended lighting is300
foot-candles. A simple light meter can measure the
3.33 Run Flat — Tyredamage resulting from operation effectiveness ofthe actual lighting.
with low or no air pressure, some times identified by
repetitive liner cracking or discoloration. 4,1.2 Anindustial-tyre vacuum systemisrecommended
toremove debris andwater from inside atyre.
3,34 Rust —Advanced stage of corrosion.
4.2 Non-destructive Testers
3.35 Section Repair — Repairs made to acasing when
The following popular devices may be used for non-
any injury extends through the tread or sidewalls of the
destructive tyre inspections.
tyr?.Thedamagedcordisremovedandreplacedbyarepair
unit, 4.3 Oliver Tuff Scan 11
This unit has a ultra high frequency systems to detect
3.36 Separation — Pulling apart of plies (from each
internally defects.Thisunithasthecapability ofsidewall-
other), such as ply separation or tread separation (from
to-mid-sidewall range of inspection. A tyre defect will
plies).
automaticallytrigger adevicethatmarksthedefectedarea
withsmallspots ofpaints. This unit maybe usedwithout
3.37 Shaping — But%ngacasingtoashapethatproperly
buffhg the tyre.
fitsthecontour ofamatrix cavity.
4.4 Hawkinson NDT II
3.38 Sidewall Separation — Separation of the rubber
compounds andplies inthe sidewall. These are three Hawkinson NDT units — trucks,
passtmger/truck combination, and a casing analyzer to
3.39 Sizing — Measurement of casing to determine the detect nail hole penetration from mid-sidewall-to-mid-
propermould fit.Usually acombination ofbead-to-bead, sidewalIduring inspection. These unitsoperate onahigh
cross-section and diameter of a circumference. Also frequency electric systemthat emits avisible sparkwhen
referred to asmould tlment. nailholeorpenetration isdetected.Thesetesterscanstand
alone or bemounted on aspreader. This unitcan alsobe
usedwithout bufl%g thetyre.
3.40 Spot Repair — Replacement ofrubber inaninjury
that penetrates lessthan 25 percent ofthebody plies.
4.5 Matteuzzi Testing Machine
3.41 Turn Tread — Small piecesoftread tornoffduring This unit isdesigned for testing casings, The tester uses
extraction from mould innew orretreaded tyres. pressuretocausesidewalltoshowweaknessesanddefects
2
IS 15731:2006
during inflation. The tyre inflated in three stages with e) Deepcuts inthetyrebodyplyinthenon-repairable
pressure ranging from 1.4to 8.3 bars, while the operator bead area;
looks for any unusual humps, bulges, or irregularities in
f) Excessively loose liner atthe bead toe;
the sidewall.
g) Note anydeformations ofthebeadduetoimproper
mounting or excessive wear; and
4.6 Casing Storage
h) Wheninspectingthetreadarea,markwithacrayon
Tyresandmoisture (water) areenemies, particularly ifthe
moisture isinsidethetyreorininjurymoisture penetrates to indicate the starting point.
through casing, the inner-liner can cause havoc with the
5.4 Tread Conditions
structure of atyre body. If the tyre isa steel radial truck
tyre, moisture penetration can cause the steel cables to a) Damage requiring repairs to be placed too close
rust and corrode. This could weaken the strength of the together;
steelcablesandleadtopremature failure.Inthetyrefabric,
b) Tyreswithtread breaker, belt, orply separation;
moisture may cause weakness or separation between the
c) Excessive wear, making buffing impossible for
plies.Alltyrestoberetreaded shall bemoisture-free and
mould or precure retreading;
stored indry areas. These areas should protect the tyres
fromrain,fog,snow,ice,etc.Tyresshould notbelacedor d) Excessive rust inradial tyre belt package;
thrown together in a haphazard fashion. This tends to e) Deepregrooving thatexcessivelydamagesthebelt;
distortsteelbeltsandresultsinproductsthatthump,bump,
9 Cutting, tearing and chunking which cause
or have crooked treads. The best wayto store tyres isto
excessive exposed belts;
stackthemflatinpilesnohigherthan eightpassenger and
lighttruck, ormedium truck tyres. g) Tread injuriesthatfalloutsidetheacceptablerepair
limits;
5 INSPECTION h) Useanawltoprobe allcutsandpenetrations. Mark
allpunctures. Markalldeepcutsforrepairorreject,
5.1 Tyresshouldbeinspected indryandcleancondition. iftoo deep ornon-repairable. Watchforrust spots
A wet vacuum is to be used to remove water and then inthe tread cuts of steel radial tyres; and
wipethetyredry.This should be done the daybefore the
j) Note sidewall damage — lacerations, cuts, etc.
inspection to allow the casing to dry thoroughly. Tyre
Watch for broken sidewall body cables in radial
punctures, inner liner splits and other damages may go
truck tyres. Mark allrepairable damage.
undetected inwetor dirty tyres.
5.5 Sidewall Conditions
5.2 Causes for Rejection
a) Side wall injuries that fall outside the acceptable
a) Broken or loosecords beyond repair limits;
repair limits;
b) Excessive cracking;
b) Separation or deep cracking insidewall atthe ply
c) Plyseparation; turn up. A very thorough inspection of the area
d) Excessivetool damage; ranging up to 25.4 mm outside the G-G (rim
aligning) ring onthe lowersidewall mustbemade.
e) Non-repairable (open) liner splices;
Expanding beads laterally with certain spreaders
o Runflat;
can showthis separation;
g) Tubeless tyres with visible bond ply through the
c) Wildwirethrough the tyre sidewall;
linerstock and splice opening;
d) Sidewall separations orbroken wiresappearing as
h) Badcable;
bulges;
j) Excessive or large linerblisters; and
e) Tyres having sidewall separations, bruise breaks,
k) Previous repairs showing signs of failure or
andbow outs;
unreliability.
o Circumferential or radial cracking due to flexing
5.3 Bead Conditions or deep branding;
a) Bent,distorted, or broken beads; ?3)Non-repairable flow cracks;
b) Excessive cracking or chafing area. In bias tyres, h) Tyres with weather cracking in sidewall/shoulder
minor chafer fabric damage canbe spot repaired; areas as follows:
1) Deeper than 2,4 mm not acceptable;
c) Tyreshaving ply or chafer separation;
2) 1.6mmto 2.4 mm for trailer application only;
d) Cutspenetratingthewirethathavecausedrustand/
orseparation; 3) Upto 1.6mm for trailer application.
3
1S15731:2006
j) Besurethat the condition isweather cracking and d) Evidence run flat or low; )
not flex cracks. Weather cracking should not form
e) Injuryto theply cord fabric inthebead area;
aconnected line; ,,
f) Temporary plugs inthe sidewall area;
k) Tyrescontaminated with oil and grease; k
g) Casings with previous section repairs to damage
m) All radial tyres that have been punctured or outside specified injury limit; and 4
previously repaired should be carefblly inspected
h) Nail holes larger than 6.4 mm.
in the sidewall area for broken or weaken cable 1
damage. If the tyre is accepted for retreading but
5.7.3 Truck tyres accepted for retreading shall not !:
needs repairs, mark any and allrepairs onthetyre
contain anyofthe following weaknesses or injuries
andthetyre cord; and 1!
a) Ply separation; f
n) Be careful when stapling tyre tags on steel radial
~“
tyres. Stapleholesallowmoisture topenetrate into b) Broken, damaged, kinked, orexposed beadwires; ~.
thetyrebody.Confine anystaplingtothetreadarea c) Injuries to theplies inthe bead are%
~
only.
d) Flex breaks; ~
(
e) Loosecordsontheinsideplyorevidenceofhaving
5.6 Assorted Problems t.
been under inflated or overloaded;
a) Pinhole inbead area; ,,
f) Tread separations;
b) Lowair pressure; and
g)Weatherchecking that extends tothe body plies;
c) Porous liner.
h) Non-repairable damage to the inner liner or bead
sealing areas; and
5,7 Acceptance Criteria of Casings
,}
Passenger and light truck tyres casings showing any of -i) Worntotheplies onmore than 10percent ofworn
tyre circumference except where breaks or belts
thefollowing weaknesses or injuries or damage shallnot
arereplaced or added.
beaccepted forretreading.
5.7.4 In addition to above tyres showing any of the
5.7.1 External
following damage shall notbe accepted for retreading
a) Exposed fabric or belt material inthe tread area;
a) Extensive cracking extending through to the
b) Plyseparation;
carcass;
c) Broken belts;
b) Carcass penetrations or damage to casings above
d) Excessive oxidation; “H’ speed symbol except where these casings are
e) Surfacecutsthatpenetratethecordbodyandexceed to be down rated to a lower speed symbol;
the sizeofarepairable injury; c) Carcass break up;
f) Broken orkinked beads; d) Appreciable oil or chemical attack
g) Damaged beads exposing the ply cord area; e) Multiple damage too close together;
h) Radial cracking; 0 Bead damage other than minor ‘rubber only’
j) Circumferential cracking; and damage;
k) Improper labelling. g) Exposed cords due to tread wear or sidewall
scuf%ng;
5.7.2 Internal h) Non-repairable tread or sidewall material
a) Flexbreaks, X-breaks, or impact breaks; separation from the carcass;
b) Porous or loose liners; j) Structural damage inthe area ofthe sidewall; and
c) Defective inner liner splices beyond repair limits; k) Corroded steel cord orbead wire.
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should ascertain that they are inpossession ofthe latestamendments oredition byreferring tothe latest issue of
‘BIS Catalogue’ and’ Standards :Monthly Additions’.
This Indian Standard has been developed from Doc :No. TED 7 (465).
Amendments Issued Since Publication
Amend No. Date of Issue Text Affected
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