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Commercial Medium Tire Debris Study
Alrik L. SvensonResearch Engineer
Office of Applied Vehicle Safety Research National Highway Traffic Safety
AdministrationWashington, D.C.
SAE Commercial Vehicle Engineering Congress & Exhibition
Rosemont, IL October 7, 2009
Acknowledgement
This study was performed for NHTSA by the University of Michigan Transportation Research Institute (UMTRI)
John F. WoodrooffeOliver A. PageDaniel BlowerPaul E. Green
Tire failure analysis was performed by Smithers Scientific Services in Akron, OH
Michael Blair and associates
Outline
o Objectiveso Previous Studieso Crash Data Analysiso Tire Debris Collection Siteso Tire Debris Collection Plano Tire Failure Analysis Taskso Resultso Conclusions
Objectives
o Investigate the underlying causes of tire failures in heavy and medium duty trucks
o Determine the extent of truck tire failures for retread tires
o Determine the crash safety problem associated with heavy truck tire failures
Previous Studies
NHTSA1,496 pieces86,028 lbs
UMTRINationalSummer2007
Bridgestone Firestone
10,291 tiresWeight Unknown
Bridgestone FirestoneNationalVarious2005
Virginia GeneralAssembly
27 tires &127,522 lbs of
debris
Department ofState PoliceVA & VDOT
VirginiaSummer2000
ArizonaDOT
859 piecesWeight Unknown
Jason CareyPhoenix,AZ
Summer1999
AmericanTrucking
Association
2,200 piecesWeight Unknown
Technology MaintenanceCouncil (ATA)
NationalSummer1998
AmericanTrucking
Association
1,720 piecesWeight Unknown
Technology MaintenanceCouncil (ATA)
NationalSummer1995
SponsorPieces Analyzed/ Weight
Collected (lbs)
Executing OrganizationLocationSeasonYear
Crash Data AnalysisIdentify Scope and Nature of the Effects of
Truck Tire Failures in Crash Recordo Direct effect - tire blowouts or loss of tread in
truck crashes.o Indirect effect - traffic crashes related to truck
tire debris left in the roadway.
Crash Databases Considered: o Trucks in Fatal Accidents (TIFA) 1999-2004o General Estimates System (GES) 2002-2005o Large Truck Crash Causation Study (LTCCS)
Total Defects Coded For Trucks
0.120Signals
0.118Headlights
0.07Exhaust System
0.126Power Train/Engine
0.136Suspension
0.142Steering
0.9269Tires
1.9589Brake System
93.128,861None
100.031,016Total
0.395Other
0.01Air Bags
0.015Wheels
0.141Trailer Hitch
0.08Body, Doors, Other
0.02Wipers
0.04Horn
0.145Other Lights
Source: TIFA 1999-2004
Defect Coded Number % Defect Coded Number %
9,9169,816100Total17170Unknown severity1,2671,25710C-injury1,5771,56116B-injury1,5271,50819A-injury5,5295,47455Fatal
TotalNo Tire Defects
Tire Defects
Injury Severity
Source: TIFA 1999-2005 Annual Average
Annual Fatalities and Injuries in Fatal Truck Crashes By Coded Tire Defects
First Harmful Event for Fatal Crashes with Coded Tire Defects Vs. No Tire Defects
0.0 10.0 20.0 30.0 40.0 50.0 60.0 70.0 80.0
Hit motor vehicle
Non-fixed object
Fixed object
Other non collision
Rollover
Firs
t har
mfu
l eve
nt
Percentage of fatal crash involvements
Tire defects
No tire defects
Source: TIFA 1999-2005
Fatal Crash Involvements by Month
0.0
2.0
4.0
6.0
8.0
10.0
12.0
14.0
16.0
Januar
y
Febru
ary
Mar
chApril
May
June Ju
ly
August
Septe
mber
October
Novem
ber
Decem
ber
Per
cen
tag
e o
f in
volv
emen
ts No tire defects
Tire defects
Source: TIFA 1999-2005
Incidence of Coded Tire Defects in Fatal Crashes by Posted Speed Limit
Source: TIFA 1999-2005
0.0
0.5
1.0
1.5
2.0
2.5
<=25mph
30 mph 35 mph 40 mph 45 mph 50 mph 55 mph 60 mph 65 mph 70 mph 75 mph
Posted speed limit
Per
cent
tire
def
ects
Incidence of Coded Tire Defects by Truck Model Year
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1980 - 84 1985 - 89 1990 - 94 1995 - 99 2000 - 04
Per
cen
tag
e w
ith
tir
e d
efec
ts
Source: TIFA 1999-2005
Rollover for Trucks Coded with Tire Defects Vs. No Tire Defects
0.0 20.0 40.0 60.0 80.0 100.0
No tire defects
Tire defects
Percentage of involvements
Subsequent Event
First Event
No Rollover
Source: TIFA 1999-2005
Jackknife for Trucks Coded with Tire Defects Vs. No Tire Defects
0.0
1.0
2.0
3.0
4.0
5.0
6.0
7.0
No tire defects Tire defects
Pe
rce
nta
ge
wit
h ja
ck
kn
ife
First Event
Subsequent Event
Source: TIFA 1999-2005
Tire Debris Collection Sites
Tucson AZ
Taft CA
Gainesville FL
Wytheville VA
Gary IN
Tire Debris Collection Plan
o Tire debris collected from State DOT yards for a 2 week period at each site
o Only casings/shreds from large trucks (tractor/trailers 10,000 lbs or more)
o Tire debris collected is a minimum 2 ft in length and 4 inches wide
o Discarded truck tire casings were collected from area truck stops for each site
o A 53’ trailer was loaded at each site and sent directly to Smithers for analysis
Tire Debris Collected in Wytheville, VA
Truck Casings Collected at IN Truck Stop
Tire Failure Analysis
o Conducted at Smithers Akron facilityo Visual, tactile, non-destructive examinations were
conducted on each tire fragment/casing sampleo Study team consisted of 6 expert personnel (plus
support staff)o A database was constructed from the examinations
for each sampleo Cause of failure determination for each sampleo Photographic record of representative samples
Failure Analysis Categories
•Excessive Wear•Skid-Through•Petroleum Damage•Improper/Failed Repair•Mounting Damage•Vehicle Damage•Un-repaired Puncture•Incorrect Application
Maintenance/Operational
•Cut/Snag•Impact Break/Rupture•Radial Split•Pinch Shock•Crown Penetration•Sidewall Penetration
Road Hazard
●Damage From Excessive HeatExcessive Heat
•Tire Was Run While Flat•Sidewall Flex Fatigue Rupture •Detachment
o Tread onlyo Tread and outer belt(s)o Tread & belts from casing
•Three-Piece Flex Break
Overdeflected Operation
Damage/Failure Sub-CategoryDamage/Failure Category
Failure Analysis Categories (Cont.)
•Bond Failure/Separation (Retread)•Improper Repair•Missed Repair •Questionable Remaining Casing Life•Tire manufacturer Issue•Other
Manufacturing/Process Issues
•Indeterminate CausesIndeterminate
•Compromise of Inner Liner•Bead Damage•Other
Excessive Intra-carcass Pressurization
Damage/Failure Sub-categoryDamage/Failure Category
Results - Fragments by Retread Status
1,19614.2%17067.9%81217.9%214Total
25913.5%3573.4%19013.1%34Wytheville VA
32814.6%4866.8%21918.6%61Tucson AZ
25018.0%4565.6%16416.4%41Taft CA
1615.6%970.8%11423.6%38Gary IN
19816.7%3363.1%12520.2%40Gainesville FL
TotalUnknownRetreadOriginal TreadCollection Site
Tire Casings & Fragments Failure Category Determination
0
5
10
15
20
25
30
35
40
45
1 2 3 4 5 6 7
Damage/Failure Category
Per
cent
Casings Fragments/Debris
Damage/Failure Categories:1 – Overdeflected Operation2 – Excessive Heat3 – Road Hazard 4 – Maintenance/Operational5 – Manufacturing/Process6 – Indeterminable 7 – Excessive Intra-Carcass Pressurization
Tire Casings & Fragments Failure Category Determination (excluding indeterminate)
0%
5%
10%
15%
20%
25%
30%
35%
40%
45%
1 2 3 4 5 7
Damage/Failure Category
Perc
ent
Casings Fragments/Debris
Damage/Failure Categories:1 – Overdeflected Operation2 – Excessive Heat3 – Road Hazard 4 – Maintenance/Operational5 – Manufacturing/Process6 – Indeterminable (not shown)7 – Excessive Intra-Carcass Pressurization
Tire Casings Failure Category OE Vs. Retread
0%
10%
20%
30%
40%
50%
60%
1 2 3 4 5 6 7Tire Casing Damage/Failure Category
Perc
ent
OERetreadUnknown Damage/Failure Categories:
1 – Overdeflected Operation2 – Excessive Heat3 – Road Hazard 4 – Maintenance/Operational5 – Manufacturing/Process6 – Indeterminable 7 – Excessive Intra-Carcass Pressurization
Tire Fragments Failure Category OE Vs. Retread
0%
5%
10%
15%
20%
25%
30%
35%
40%
45%
50%
1 2 3 4 5 6 7
Tire Fragments Damage/Failure Category
Perc
ent
OE Retread Unknown
Damage/Failure Categories:1 – Overdeflected Operation2 – Excessive Heat3 – Road Hazard 4 – Maintenance/Operational5 – Manufacturing/Process6 – Indeterminable 7 – Excessive Intra-Carcass Pressurization
Tire Year of Manufacture (OE or Retread Casings)
0%
5%
10%
15%
20%
25%
30%
35%
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
DOT Year of Manufacture
Perc
ent o
f Cas
ings
(Kno
wn
Yea
r)
OE Retread
Collection Time Period: August-September 2007
Casings and Tire Fragments Probable Wheel Position
0%
10%
20%
30%
40%
50%
60%
1 2 3 4 5 6 7 8
Probable Wheel Position
Per
cen
t o
f C
asin
gs
Casings Tire Fragments
Wheel Position Categories:1 = Steer2 = Drive3 = Trailer4 = Steer or Trailer5 = Drive or Trailer6 = Steer or Drive7 = Steer or Drive or Trailer8 = Indeterminate
Failure Category Study Comparison OE/New Tires
0%
10%
20%
30%
40%
50%
60%
Belt Sep'/Indet' Road Hazard Mnfr Issues Repair Failure TireMaintenanceFailure Category
Perc
ent
TMC(1995) TMC(1998) UMTRI Casings (2007) UMTRI Fragments (2007)
Failure Category Study Comparison Retread Tires
0%
10%
20%
30%
40%
50%
60%
70%
BeltSep'/Indet'
Road Hazard Mnfr Issues RepairFailure
TireMaintenanceFailure Category
Perc
en
t
TMC(1995) TMC(1998) UMTRI Casings (2007) UMTRI Fragments (2007)
Conclusions - Crash Data
o For truck/trailer vehicles, reported tire defects ranked second after brake system defects.
o Number of crashes with reported tire defects is small: 0.9% of all crashes (TIFA).
o Crashes with reported tire defects tend to occur in warmer months and are speed related.
Conclusions - Crash Data (Cont.)
o Truck/trailer crashes with reported tire defects tend to involve older vehicles.
o Rollover was more likely in trucks/trailers with reported tire defects.
o Loss of control was more likely in trucks with a reported tire defect located on a tractor steer axle.
Conclusions – Tire Casings
o Approximately 43% casings analyzed were retreads and 57% were original tread casings.
o Top 3 reasons casings were removed from service: road hazards (33%); maintenance/operational factors (29%) and overdeflected operation (14%).
o Slightly less than 10% of all casings showed any manufacturing or process-related conditions. o Of this number, most were retreading process issues,
such as casing selection and repair, or tread rubber application issues.
Conclusions – Tire Debris
o Approximately 68% of tire fragments were from retread tires and 18% were from original tread tires. The remaining 14% could not be determined.
o Results are consistent with the estimated distribution of OE and retreads in service.
o Top 2 types of damage for debris fragments: road hazard (39%) and excessive heat (30%).
Conclusions - Overall
o Retreads were not overrepresented in the tire debris items collected.
o Results indicate the majority of tire debris collected was not a result of manufacturing or retreading process deficiencies.
o Truck/trailer vehicle crashes with a coded tire defect account for less than 1% of all crashes annually.o These crashes tend to have a higher incidence of rollover
and loss of control than crashes with no reported tire defect.
