Does your harvester need specific tyres?

Harvesting is the campaign that requires the heaviest equipment, for which you must routinely check your tyres and adapt pressure based on the different loads.


What are the physical limits of your tyres?

If you check the maximum load specified by your manufacturer for your standard tyres, you will often find that the level of weight is much higher than the maximum specified, even with maximum inflation pressure. You only have one solution, to half-fill a hopper. With more trips back and forth with the trailer required and an overall loss of time for the harvesting campaign.


1. To increase the load on the harvester tyres, you must reduce speed

Speed is not compatible with very heavy loads

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. The manufacturers have 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 is a reference point, which means that you can load more if you reduce speed or increase speed if you reduce the load.

  • What happens in the case of excess speed?

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.


2. To increase the load on harvester tyres, you must never drive on a slope of more than 20%

The bonus load is not compatible with steep inclines

As harvesting equipment is very heavy and must 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.


3. To increase the load on harvester tyres, you must limit the distance driven

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. Therefore, 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.



To obtain a bonus load of +70%: You must increase inflation pressure by 25% and drive no faster than 10 km/h, as well as respecting maximum slope and distance criteria.

To obtain a bonus load of +55%: You must increase inflation pressure by 25% and drive no faster than 15 km/h, as well as respecting maximum slope and distance criteria.

If you respect these three conditions, you will not alter the characteristics of the tyre, you should be able to maintain your tyre and increase the life span and usability.

For more information contact TyreZim to speak to a specialist in Alliance Agricultural tyres. We can be contacted on 08677 200 300 or on Email on



Referencing and more information, you can access the original article as follows:

3 rules to increase the load on your harvester tyres by 70%. [online] Available at: [Accessed 1 Jun. 2022].