How to use Ton-Kilometre per Hour

The Ton Kilometre per Hour factor is of great assistance in determining the suitability of a tyre for an operation. The following factors must be borne in mind with regards the TKPH factor when selecting a tyre.

1. Maximum operating TKPH should not exceed the tyre TKPH rating.
2. The average operating TKPH to be calculated after several checks, and should not exceed the tyre TKPH rating.
3. The TKPH rating data are applicable in the following situations:

• To all standard, heat or cut-resistant tyres.
• Ambient temperature less Than 3800.
• Maximum trip distance less than 5 km 0 16 km with reduced load.
• Maximum speed of 50 km/h. (Refer Load/Inflation Tables)

TKPH Adjustments

The TKPH factor is influenced by heat. When the heat in the tyre increases due to abnormal conditions such as high ambient temperature, speed and overloading the TKPH should be reduced. Similarly adjustments to the TKPH can be made if the ambient temperature or the speeds are low. The load carried by the individual tyre must be in line with the recommendations as specified by TREDCO. Refer to load/ inflation tables.

TKPH Conversion Factors

For temperatures in excess of 38°C - The TKPH should be reduced by approximately 2% for each degree C rise above 38°C.

For temperatures lower than 38°C - The TKPH should be increase by approximately 1% for each degree C below 38°C.

Calculating TKPH (to determine actual work rate of an operation)

1. Obtain average of empty and loaded mass per tyre in tons for each axle. (If no scales available, use specification sheet masses as best possible estimate).

Mean Tyre Load in Ton = ( Empty Mass in kg + Loaded Mass in kg  ) / ( 2 * 1000 )
 
2. Obtain overall length of round trip per haul from an engineer.
3. Obtain number of loads hauled per shift from contractor's load count.
4. Obtain total shift hours from contractor.
5. Calculate overall average speed based on Items 2, 3 and 4.

Work Day Average Speed = ( Overall round trip length * Number Loads per Shift ) / Shift Hours 
 
6. Calculate TKPH based on the HEAVIEST loaded tyre in Item I and average speed from Item 5.

TKPH =  Mean Tyre Load * Work Day Average Speed

7. If the calculated TKPH requirement is higher than the TKPH rating of the tyre being used, reduce speed and/or load or use a tyre with higher TKPH rating.