With standard tyres on your harvester, you will rapidly reach the limits in terms of bearable load or maximum pressure.
These limits are a nuisance during harvesting and you will lose time emptying the hopper more often or sometimes have to stop operations if the trailer rotations are not correctly synchronised.
Yet there is a simple solution to increase the load by 70% and continue work with less frequent unloading. The solution requires specifically designed harvester tyres which offer a cyclic load of 14 tonnes more on the front axle.
Harvesting is the campaign that requires the heaviest equipment, for which you must absolutely check your tyres and adapt pressure based on load.
With the front cutting bar and the hopper full, the weight distribution is around 75% on the front and only 25% on the rear axle.
If we take the loads in the example above, that makes approximately 14,000 kg on each front tyre.
If you check the maximum load specified by your manufacturer for your standard tyres, you will easily find that the level of weight in the example above is much higher than the maximum specified, even with maximum inflation pressure.
You only have one solution, to half-fill the hopper, with more trips back and forth with the trailer required and an overall loss of time for the harvesting campaign.
Each tyre has a speed rating linked to a load index marked on its sidewall.
This indication is very important because it gives you the nominal load and speed provided by the manufacturer, who has tested your tyre model and established, as a result of these tests, that this load associated with this speed is the optimal setting to work rapidly without damaging your equipment.
It’s a reference point, which means that you can load more if you reduce speed or increase speed if you reduce the load.
You have noticed that the load squashes the tyre into the ground. This deformation of the tyre is accentuated if you increase the load.
The travel speed determines the time your wheel will take to complete a full turn. For each rotation, the tyre must imperatively have the time to get its original shape back before coming back into contact with the ground and undergoing a further deflexion.
If this is not possible (due to excess speed) the deformation of the tyre will amplify until the casing breaks.
Reducing speed is one of the main ways to be able to increase load considerably. Here is an example with the specialist Maxi Traction Harvest tyre made by FIRESTONE.
You need great reliability of the tyre in terms of load capacity to obtain such a difference, which is possible for this specific model that has been reinforced structurally with a greater number of plies.
Front tyres 900/60 R32 Maxi Traction Harvest:
As harvesting equipment is very heavy and has to cope with cyclic loads during the filling and unloading of the hopper, its tyres are placed under considerable strain.
If you want to obtain the 70% bonus load described in the preceding examples, you must take the slope of the land into account. The degree of inclination of the slope has a direct impact on the tyres positioned lower down.
The crushing of the tyre linked to the cyclic load effectively increases more on the lower tyres. The maximum tolerance is 11 degrees, which is a 20% gradient.
Unlike with the tractor, you cannot adjust pressure to correspond precisely to your load, because the load fluctuates.
There may be a difference in weight of around 12,000 kg when the hopper is fully loaded. It is your tyres alone that compensate for this excess load.
Naturally, it’s when the load limits are exceeded that the quality of the tyre’s construction and its structure are extremely important.
In the example above, the 900/60 R32 tyre goes from 8,250 kg at a pressure of 3.2 bar to a load of 14,025 kg and a pressure of 4 bar. This is a gain of more than 5,700 kg.
This excess load cannot be constant, because it would have too great an impact on the internal structure of the tyre. This is why the distance you can drive with the maximum bonus load is only 1.5 km, which allows you to save precious time before unloading into the trailer.
you must increase inflation pressure by 25% and drive no faster than 10 km/h, as well as respecting maximum slope and distance criteria.
you must increase inflation pressure by 25% and drive no faster than 15 km/h, as well as respecting maximum slope and distance criteria.
With Firestone, you have the guarantee of tractor tyres that deliver a real advantage, and that in choosing our brand, you can work worry-free.
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