This document discusses strategies for reducing risks associated with earthmover tyre fitting and rotation in mining operations. It finds that tyre fitting is a dangerous activity that accounts for a disproportionate number of fatalities compared to other maintenance tasks. Potential strategies to reduce risks include improving tyre life, implementing smarter tyre rotation strategies, and fitting some new tyres to rear axles rather than only front axles. Case studies show this can reduce annual tyre usage and downtime by increasing average tyre life and decreasing the number of tyre changes needed. Considering the different load and speed conditions of front versus rear axles, fitting more durable tyre compounds to rear axles is also recommended when appropriate.

1. Earthmover
tyre fitment
and rotation:
Strategies for mines

2. Harry Godwin
2012
Bachelor of Materials
Engineering (Hons) –
University of Queensland
2012 – 2016
Otraco International
-Extreme tyre enthusiast
-Spend too much time looking ahead
(crystal ball style)
-Developed new automated
forecasting program specific to OTR
tyres.
-Living and breathing numbers

3. Tyre Fitting is Dangerous Work
All fatalities associated with rubber tyred equipment maintenance
(Australian mining industry, 1980 – present)
3 x tyre fitters
8 x non tyre fittersFatalities
during
non – tyre
equipment
maintenance
Fatalities
while servicing tyres
Most fatalities were caused by tyres
or rims during only 2% of total
machine hours.
Fatality risk up to 10 x
higher.

4. How do we reduce this
exposure?
 Best practice procedures
 Fit-for-purpose tooling
 Trained and competent tyre fitting
personnel
 Custom built tyre bay/changing facility
What else….?
 Improved tyre life
 Tyre rotation and fitment strategies

5. Normal Life Cycle of an OTR Tyre
 OTR haul truck tyres start life fitted
to the front axle
 After certain interval (nominally
33% of life) tyre is removed
 Placed into “run out” stock
 Then tyre is fitted to rear axle to be
“run out”

6. How to reduce the number of
tyre changes?
 Increase tyre life
 Line up major component changes and rim
Non-Destructive Testing (NDT)
 Smarter tyre rotation strategies
 Better tyre specification selection for site
application

7. The Effect of
Tyre Life on Tyre Changes
300 900
800250
NewTyreRequirementsandTyre
Changes
120
240
720
103
206
617
ProjectedDowntimeHours
Base calculation
 Number of tyre hours
required / average
tyre life
 6 tyre positions per
truck
200
150
100
50
700
600
500
400
0 300
 ~500 engine hours
Tyre Life = 6,000 hours Tyre Life = 7,000 hours
per truck per month
New Tyres Required Minimum Tyre Changes
Minimum Annual Downtime  500 x 12 x 20 =
120,000 operational
tyre hours/yearHaul Truck Fleet
-20 Trucks
-Availability: 86%
-Utilisation: 80%
Truck Config.
-Front axle: 2 tyres
-Rear axle: 4 tyres
(two sets of duals)
Change Time =
3 hours
Min. changes per
tyre = 2

8. Potential Tyre Fitment and
Rotation Strategies
Fit new tyres as required (no rotation
strategy)
Fit all new tyres to front axle positions
only
Fit a proportion of new tyres to rear
axle positions

9. Tyre Usage
and Rotation Strategy
0
50
100
150
200
NumberofTyres
Front Rotation Interval (Hours)
New-To-Front Tyres New-to-Rear Tyres
Total Tyre Requirements Run Out Tyres Required
Change @ 33% Life
Total Tyres
Required = 120
Change @ 67% Life
Total Tyres
Required = 120
Total New Tyre Requirements

10. New-to-Rear tyre fitments
Common arguments against new-to-rear fitments
 Tyres more likely to fail prematurely on the rear
 It’s preferable to lose a well worn tyre due to premature failure
Problem with these arguments
 As the proportion of new tyres fitted to the front axle increases,
front tyres have to be replaced at even lower average life
 Average haul truck life overall is independent of the proportion
of new tyres fitted by axle
 There is a considerable detrimental effect on haul truck
downtime

11. The Tyre Change Index
Tyre Change Index = Proportion of new tyre fitment to front axle + 1
 All tyres fitted new to front: Index = 2.0
 40% of tyres fitted new-to-rear: Index = 1.6
 Result – 20% decrease in haul truck downtime

12. Tonnes-Kilometres-Per-Hour
 TKPH is the work rating of a tyre.
 This work rating is similar to the load capacity of a tyre, but also
accounts for heat generation due to load, speed and flexing.
 Value given to all Earthmover tyres by manufacturers.
 In theory, if SITE TKPH is less than a rated TYRE TKPH
operation can occur with little risk of heat failures.
Operational TKPHLow High
Select more cut resistant compounds
Select more heat resistant compounds
Positives
-Slower wear
-Fewer rock cuts
-Fewer sidewall
cuts
Negatives
-Can’t tolerate
high speeds
Selected tyre
always has to
be a
compromise
Positives
-Copes well with
high speeds
Negatives
-Faster wear
-More prone to rock
cuts & sidewall
damage
TKPH = Average Work Day Speed x Average Tyre Load
 Good starting point
for tyre selection.

13. TKPH –
Real Life Data - Lower TKPH on the rear axle
0
250
500
750
1000
1250
1500
1750
2000
3:30 PM
29-Jul-15
9:30 PM
29-Jul-15
3:30 AM
30-Jul-15
9:30 AM
30-Jul-15
3:30 PM
30-Jul-15
9:30 PM
30-Jul-15
3:30 AM
31-Jul-15
9:30 AM
31-Jul-15
OperatingTKPH/TyreTKPHRating
Komatsu 930E Dump Truck
Front TKPH 4 hour moving Avg. Rear TKPH 4 hour moving Avg.
53/80R63 Bridgestone VRPS E3A E-4 53/80R63 Bridgestone VRPS E1A E-4TKPH Rating – Heat Resistant Compound TKPH Rating – Standard Compound

14. Case Study – Coal Site
 New fleet of 17 ultra-class trucks mobilised on site.
 New 53/80R63 tyres (same specification/rubber compound)
fitted to front and rear axle of most trucks.
 Batch analysis showed the following results for tyre life.
TyreLife(Hours)
Average Tyre Life by Fitment Axle
6,500
6,250
6,000
5,750
5,500
New Fitments (2011-2012)
New-To-Front New-To-Rear
5,926
6,285
No corrections for
uneven wear
completed
New-to-Front
30 tyres fitted
2.7 changes per tyre
New-to-Rear
54 tyres fitted
1.9 changes per tyre
-43 tyre changes saved
-Tyre life ~4% higher

15. Case Study – Hard Rock
 220 tonne truck fleet (20 trucks) – 40.00R57 tyres
 New tyre fitments occurred 2011-2012
 Standard Compound (regular TKPH rating) – front axle
 Abrasion/Cut Resistant Compound (low TKPH rating) – rear axle
(seasonal)
Stnd Tyres
-Life = 3,898 hrs
-New Tyres = 178
Changes/tyre = 4.0
Cut Resistant Tyres
-Life = 4,376 hrs
-New Tyres = 53
Changes/tyre = 3.5
Est. Cost = $8.085M
Total Changes = 898
Downtime = 1,041
Standard Tyres
-Life = 3,969 hrs
-Equiv. New Tyres =
238
Est. Cost = $8.325M
Total Changes = 951
Downtime = 1,105
Recommended
Practice
Standard
Practice

16. Two Pronged Approach:
Tyre Selection and Fitment Policy
0
50
100
150
200
NumberofTyres
Front Rotation Interval (Hours)
New-To-Front Tyres New-to-Rear Tyres
Total Tyre Requirements Run Out Tyres Required
Tyre Life: New-to-Front = 6,000 hours
New-to-Rear = 7,500 hours
Tyre Changes: Front Fitments = 2
Rear Fitments = 1
100% New-To-Front
New Tyres = 120
Tyre Changes = 240
Front Rotat. Int. +50%
80 Tyres New-To-Front
32 Tyres New-to-Rear
Tyre Changes = 192

17. Potential Benefits
 Reduced annual tyre usage by 8
 @ $50,000 / tyre = $400,000
 Reduced minimum tyre changes by 48
 At 3 hours/change = 144 hours tyre related downtime
 Fitting tyres new-to-rear the most effective
method to rectify run-out stock levels
 Wear rates decreased – Asymmetric (uneven)
wear severity reduced

18. Summary
 Easy change to tyre management practices on site
 Check TKPH requirements of front and rear axle for
your major haul truck fleets
 Fit more cut resistant tyres to rear axle (if
appropriate)
Benefits
 Lower exposure to high risk tyre change activities
 Increased truck availability (fewer tyre changes)
 Increased tyre life
 Reduced annual tyre usage for haul fleets

19. Thank You
4th August 2016