Presentation sildes taken to document Commercial Tire Retreading class at Internation Tire and Rubber Association. In 2002 ITRA merged with TANA to form the current Tire Industry Association (TIA)

1. Commercial Tire Retreading
Robert C. McElroy, Ph.D.
www.ForensicAccident.Com
Canadian Association of Technical Accident Investigators and Reconstructionists - 1999 1

2. Tire Definition
Bubba
Academic big & dirty
flexible pressure vessel flat-on-bottom
Canadian Association of Technical Accident Investigators and Reconstructionists - 1999 2

3. Retread Training Program
Dr. McElroy Attended ITRA Training
Institute 40 Hour Commercial Tire
Retreading Class
Canadian Association of Technical Accident Investigators and Reconstructionists - 1999 3

4. Retreading Is:
•
Bonding a new
tread to a worn
tire casing
Canadian Association of Technical Accident Investigators and Reconstructionists - 1999 4

5. What is a Worn Casing
•is a properly
It
maintained tire that
has worn out its useful
tread life and been
removed from service
for retreading.
Canadian Association of Technical Accident Investigators and Reconstructionists - 1999 5

6. Vulcanizing or Curing
•
Process of chaining
macromolecules
together.
Canadian Association of Technical Accident Investigators and Reconstructionists - 1999 6

7. Vulcanizing Involves
•
Time
•
Temperature
•
Pressure
Canadian Association of Technical Accident Investigators and Reconstructionists - 1999 7

8. Tire Classification
•
Passenger
• Truck
Light
•
Medium Truck
•
Heavy Truck
•
Off-Road
•
Aircraft
•
Agricultural
•
Industrial / Mining
•
Racing
Canadian Association of Technical Accident Investigators and Reconstructionists - 1999 8

9. Tire Retreading Involves
•
Inspection
•
Repairing
•
Buffing / Skiving
•
Cementing / Filling
•
Tread Application
•
Wicking / Enveloping
•
Vulcanization
• Inspection
Final
Canadian Association of Technical Accident Investigators and Reconstructionists - 1999 9

10. Mold Cure Retreading
Canadian Association of Technical Accident Investigators and Reconstructionists - 1999 10

11. Pre Cure Retreading
Canadian Association of Technical Accident Investigators and Reconstructionists - 1999 11

12. Today’Professional Retreader
s
Must Know & Understand
• construction
Tire
• sizes & what they
Tire
mean
• usage & application
Tire
• maintenance
Tire
•
Tread design &
functions
•
Retread processing
technology
Canadian Association of Technical Accident Investigators and Reconstructionists - 1999 12

13. Maintenance &
Wheel Position
Canadian Association of Technical Accident Investigators and Reconstructionists - 1999 13

14. Tread Compounds
Should Have:
• heat generation
Low
• traction
Good
• tear resistance
High
• rolling resistance
Low
Canadian Association of Technical Accident Investigators and Reconstructionists - 1999 14

15. Rolling Resistance
Is Affected By:
• load
Tire
•
Inflation
•
Tread compound
• construction
Tire
•
Tread depth
•
Tread design
Canadian Association of Technical Accident Investigators and Reconstructionists - 1999 15

16. Road Factors
•
Surface Characteristics
•
Water depth
•
Temperature
Canadian Association of Technical Accident Investigators and Reconstructionists - 1999 16

17. Vehicle Factors
•
Speed
•
Mode of operation
•
Suspension
•
Braking system
•
Types of load
–
liquid
– CG
high
Canadian Association of Technical Accident Investigators and Reconstructionists - 1999 17

18. Heat History
• quantity of heat accumulated
The
over a period of time.
Canadian Association of Technical Accident Investigators and Reconstructionists - 1999 18

19. Tire Heat Exposure
•
Original manufacturing
temperatures.
•
Original tread life
operating temperatures.
•
Retread process
temperatures.
Canadian Association of Technical Accident Investigators and Reconstructionists - 1999 19

20. Typical Radial Truck Tire
Operating on the Road
200o F 93o C
Canadian Association of Technical Accident Investigators and Reconstructionists - 1999 20

21. Typical Radial Truck Tire
Original Tread Life
200,000 to 250,000 Miles
320,000 to 400,000 KM
Canadian Association of Technical Accident Investigators and Reconstructionists - 1999 21

22. Loads
Heat buildup area
Canadian Association of Technical Accident Investigators and Reconstructionists - 1999 22

23. Tire Inflation Pressure
• / under inflation.
Over
•
Buffed too round / too
flat.
• retread / narrow
Wide
retread.
• / narrow
Wide
processing rims or
narrow road rims.
Canadian Association of Technical Accident Investigators and Reconstructionists - 1999 23

24. Low Air Pressure
•
Increases running
temperature.
•
Reduces fuel economy.
•20% reduction in
A
inflation pressure
causes a 16% reduction
in tread life.
Canadian Association of Technical Accident Investigators and Reconstructionists - 1999 24

25. Effects On Tread Wear
• inflation by 10%
Over
reduces tread life 5-
8%.
• inflation by 20%
Over
reduces tread life 16%.
•
Matching duals
•
Torque, braking,
stopping & cornering.
Canadian Association of Technical Accident Investigators and Reconstructionists - 1999 25

26. To Select Tires for Retreading
•
Manufacturing defects
•
Non-repairable
damage
•
Excessive age
• tire be retreaded
Can
again?
Canadian Association of Technical Accident Investigators and Reconstructionists - 1999 26

27. Inspect Tires
•
Physical inspection
–
hands
–
grazing light
•
Electronic inspection
•
Ultrasonic inspection
• destructive
Non
testing
•ray
X
Canadian Association of Technical Accident Investigators and Reconstructionists - 1999 27

28. Electronic Inspection
Canadian Association of Technical Accident Investigators and Reconstructionists - 1999 28

29. Physical Inspection
Canadian Association of Technical Accident Investigators and Reconstructionists - 1999 29

30. Non Retreadable Tires
•
Damaged cord • blister
Liner
•
Improper repair • heat stress
Liner
•
Chipped bead •
Mount/demount damage
•
Broken body plies •
Improper repair
•
Zipper rupture • splice separation
Liner
•
Sidewall separation • damage
Liner
• stress
Flex •
Regroving damage
• turnup separation
Ply • deterioration
Age
Canadian Association of Technical Accident Investigators and Reconstructionists - 1999 30

31. New Tire DOT Codes
DOT MC 31 2XOW 086
• - Meets or exceeds DOT safety standards
DOT
• - Manufacturer & plant code
MC
•
2XOW - optional identification symbols
• - date of manufacture (08 week, 1996)
086
Canadian Association of Technical Accident Investigators and Reconstructionists - 1999 31

32. Retread Plant DOT Codes
R - ARA CI XXX 086 FI
• identifies as retread
R-
• - shop identification code
ARA
• - identifies matrix that the tire was
C1
cured in or is a tire size code
• - optional grouping
XXX
• - date code
086
• - steer axle option
F1
Canadian Association of Technical Accident Investigators and Reconstructionists - 1999 32

33. Buffing Template Shape
Canadian Association of Technical Accident Investigators and Reconstructionists - 1999 33

34. Buffed Radius Check Gauge
Canadian Association of Technical Accident Investigators and Reconstructionists - 1999 34

35. Buffing Machine
Buffing Head
Template
Canadian Association of Technical Accident Investigators and Reconstructionists - 1999 35

36. Apply Cement To:
•
Protect buffed surface & exposed cords
from oxidation.
•
Improves adhesion by providing for more
“intimate contact” to buffed casing.
Canadian Association of Technical Accident Investigators and Reconstructionists - 1999 36

37. Cement Tire Casing
Canadian Association of Technical Accident Investigators and Reconstructionists - 1999 37

38. Cement = Rubber Solids
Dissolved in Solvents
•
Allow 15 minutes to dry after application.
•
Install tread within 12 hours.
•
Chemical
• vulcanizing
Black
•
Concentrated or brush
•
Spray
•
Extruder or hot tack
Canadian Association of Technical Accident Investigators and Reconstructionists - 1999 38

39. Cement Application
Canadian Association of Technical Accident Investigators and Reconstructionists - 1999 39

40. Gum Cushion Application
•
Apply gum cushion
base material,
• a prepared casing.
To
Canadian Association of Technical Accident Investigators and Reconstructionists - 1999 40

41. Gum Cushion to Tire Contact
Canadian Association of Technical Accident Investigators and Reconstructionists - 1999 41

42. Trim Gum Cushion
Canadian Association of Technical Accident Investigators and Reconstructionists - 1999 42

43. Gum Cushion Base Material
•
Pressure roller ensures
attachment of gum
base material to
prepared casing.
Canadian Association of Technical Accident Investigators and Reconstructionists - 1999 43

44. Precure Tread Installation
•
Texturize tread end & cement.
• tread straight holding tightly.
Feed
• cut point even or slightly longer.
Mark
• straight & match tread design if possible.
Cut
• cushion between tread ends.
Place
• splice with least amount of hump.
Butt
• rubber toward splice & from center out.
Work
•
Install DOT identification code.
•
Apply poly.
Canadian Association of Technical Accident Investigators and Reconstructionists - 1999 44

45. Precure Tread
Installation & Cutting
Canadian Association of Technical Accident Investigators and Reconstructionists - 1999 45

46. Gum Cushion Base Material
Connects Tread Ends
Canadian Association of Technical Accident Investigators and Reconstructionists - 1999 46

47. Poly Installation
Canadian Association of Technical Accident Investigators and Reconstructionists - 1999 47

48. DOT Identification Code
Installation
Canadian Association of Technical Accident Investigators and Reconstructionists - 1999 48

49. Select Tire Envelope
Canadian Association of Technical Accident Investigators and Reconstructionists - 1999 49

50. Envelope on Expander
Canadian Association of Technical Accident Investigators and Reconstructionists - 1999 50

51. Envelope Expanded
Canadian Association of Technical Accident Investigators and Reconstructionists - 1999 51

52. Tire Insertion
Canadian Association of Technical Accident Investigators and Reconstructionists - 1999 52

53. Envelope Adjustment
Canadian Association of Technical Accident Investigators and Reconstructionists - 1999 53

54. Rim & Flange Installation
Canadian Association of Technical Accident Investigators and Reconstructionists - 1999 54

55. Prepared Tires For Chamber
Canadian Association of Technical Accident Investigators and Reconstructionists - 1999 55

56. Curing in
Autoclave or Chamber
Canadian Association of Technical Accident Investigators and Reconstructionists - 1999 56

57. Track Installation
Canadian Association of Technical Accident Investigators and Reconstructionists - 1999 57

58. Envelope & Rim
Pneumatic Connections
Envelope
Rim Connection
Connection
Vacuum
Pressure
Canadian Association of Technical Accident Investigators and Reconstructionists - 1999 58

59. Seal & Lock Chamber
Canadian Association of Technical Accident Investigators and Reconstructionists - 1999 59

60. Set Time & Temperature
Canadian Association of Technical Accident Investigators and Reconstructionists - 1999 60

61. Post Vulcanization
Canadian Association of Technical Accident Investigators and Reconstructionists - 1999 61

62. Final Inspection
Canadian Association of Technical Accident Investigators and Reconstructionists - 1999 62

63. References
Canadian Association of Technical Accident Investigators and Reconstructionists - 1999 63

64. Canadian Association of Technical Accident Investigators and Reconstructionists - 1999 64

65. Canadian Association of Technical Accident Investigators and Reconstructionists - 1999 65

66. Dr. McElroy Examining Retreaded Tire The End
Canadian Association of Technical Accident Investigators and Reconstructionists - 1999 66