Tires

Tire Selection: Considerations

1. Will it fit?
2. Will it carry the load?
3. Is the design suitable for the underfoot conditions?
4. Does the tire meet TKPH/TMPH requirements?

Functions: carry the load, cushion loading & haul impact, transmit driving & braking force, provide flotation, directional stability & cornering

Tire Types

1. Radial vs bias ply
strength, flexibility
2. Wide base vs regular width
flotation, contact area, comfort
3. Duals vs single
load capacity, rolling resistance
4. Regular vs deep tread
cooling, grip action, rock cut resistance





Radial or Bias?
Komatsu Handbook





Wide Base Tires



Extra Wide Base Tires



Tire Selection
Komatsu Handbook



Tire Life Factors

1. Proper selection (size) & rating
2. Operating within capabilities: TKPH
3. Haul road design & m-ce
* curves, grades, smoothness, firmness, cleaning of spillage
4. Tire maintenance:
* inflation, matching, repairs
5.Operator skill: speeds, stopping manner
6.Inspections: cuts, rim damage, etc

Tones-Miles-Per-Hour (or is it TKPH?)

1. TKPH is a performance rating of a tire defied as a product of:
2. Average Tire Load (tones)
3. Average Shift Speed (KPH)
4. Average tire load:
(Load empty + load full) / 2
5. Average tire speed:
(Round trip distance x No. of trips) / (No. of hours worked)

TMPH / TKPH







TMPH - Other Issues

1. Separate ratings for TMPH, TKPH
2. Ratings defined for 370C (1000F)
* corrections required if ambient temp. differs (always?)
3. Check all tires (load distribution varies)
4. Length of haul may impact the rating
* Correct TMPH for hauls over 5 km (Mich.)
* Correct TMPH for hauls less than 5 km (Brdg)
* Other……..
* Empty and loaded run are not always the same

Manage the cycles to fit TMPH !!!

Tire Wear

1. Fatigue wear
a. “ideal conditions”, tire life over 10,000 hrs
2. Thread wear - “worn-out”
a. the most desirable; consider compound
3. Cuts: face, side
* look at application; m-ce, operation & road cleaning all are important
4. Heat damage - “separation”
* are the tires overloaded? Too long cycles?
5. Running on underinflated tires?
6. Blowouts

How to Measure Wear?

1. Wear per distance run?
a. How do we measure how many were run?
b. Consider short cycle with lots of idling
* vs. log cycles, no idling
c. The best: relates wear to work done
d. Dispatch systems?

2. Wear per operating hour ?
a. Engine hour-meters? Easy to measure
b. How accurate?

Tire Thread





Tire Maintenance

1. Inflation pressure checks
a. hot: daily, cold: weekly
2. Periodic rotation program:
a. mach type, diameter, new tires on
* front wheels, rotate rears (see next slide)
3. New tires with new valves & o-rings
4. Never weld on rim with a tire on
5. Never use steel hammers on rim parts

Tire Rotation



1. New tires on front axle (LF, RF) till 20-50% worn
a. highest reliability: safety
b. steering
2. Rotate to inside rear (RIR, LIR)
3. Rotate to rear outside (LOR, ROR)
a. easy to change

Tire Size and Performance