# Do you know the real OPERATING COST of your tyres?

Without prejudice do you know the real operating cost of your tyres and related issues? Many companies record tyre history and track the historical cost. However this does not reflect the actual costs to your company. I will use an example; (Haul Trucks Only)

1. A company has 34 Haul Trucks with 6 tyres each truck = 204 wheels & tyres.
2. Average cost per tyre of 9500.00 USD per tyre (2700R49)
3. Average working life of 8500 Hours
4. 204 tyres x 9500.00 USD = 1,938,000.00 USD
5. 204 tyres x 8500 hours worked = 1,734,000.00 hours worked
6. 1,938,000.00 USD = 1.11 USD cost per hour / per tyre
1, 734,000.00 hours worked

The above calculation is based on ideal target conditions.

It is common opinion that up to 40% of tyres being operated in mine sites are at least 10% under inflated due to improper maintenance. The air inside a tyre is the single most important component to a haul truck, without air your truck would be sitting on its wheels unable to move. The air is also the single most important component to a tyre; the air pressure gives a tyre its shape & allows a tyre to roll. Should your tyre be under inflated the shape will change affecting its ability to roll. A 10% decrease in air pressure (under inflation) will result in up to a 16% reduction in tread life.

1. 204 x 40% = 81.6 under inflated tyres
2. 8500 hours x 16% reduction in life = 7140 hours
3. 7140 hours x 81.6 under inflated tyres = 5,82,624 hours
4. 204 â€“ 81.6 under inflated tyres = 122.4 target tyres
5. 122.4 x 8500 = 1,0,40400 target hours
6. 1,0,40400 target hours + 5,82,624 under inflated hours = 1,623,024 hours worked
7. 1,938,000.00 USD cost = 1.19 USD cost per hour
1,623,024 hours worked

From the above equation we can calculate the cost to your company of under inflated tyres at;

1,734,000 potential hours x .09 c increase in cost per hour = 1, 56,060.00 LOSS in under inflated tyres.

To make matters worse, hour meters are not a true reflection on the amount of work applied to the tyre. As in all load & carry situations a Haul Truck will spend a considerable amount of time stationary whilst being loaded, waiting to be loaded & unloading. Because of this modern trends are to base our calculations on kilometers traveled as this gives a true reflection of the amount of work applied to a tyre.

Should one apply these figures to the equation, the sum is very different indeed.

This is only one of a string of factors that relate to the ability of a mine site to reduce tyre operational costs. As we add more Haul Trucks, Loaders, & Service Vehicles to the equation, also premature failures due to operating issues we will begin to reflect the true cost rather than simply tracking a tyre to give a historical cost.