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The wrong tyre pressures and other variables will lead to excessive fuel costs

Some of the variables that have the most considerable effect on fuel consumption are easy to manage.

For example, tyre pressure selection is directly linked to excessive fuel consumption. Unnecessary use of counterweights is another fuel drain.

The importance of matching the tyres on your tractor to the work that it is carrying out cannot be overstated. Tyres are the conduits through which mechanical power is passed to the ground.

The efficiency of the delivery of that power depends on the condition and inflation pressure of the tyre.

Contrary to popular opinion, Michelin tests have demonstrated that tyre over-inflation can lead to a bigger fuel drain in field conditions, especially in tillage applications.

Over-inflation results in the tyre leaving a deeper footprint in the field.

More diesel is burnt in both the making of that footprint and in the tractor's attempt to pull out of a deeper rut than is necessary to maintain traction. This all contributes to greater rolling resistance.

The other disadvantage of over-inflated tyres is wheel-slip. If your wheels are slipping, the efficiency of power delivery rapidly reduces.

Though power is being created and fuel is being used, less work is being done.

On the other hand, too low a tyre pressure is also a drain on diesel because the energy required to move the tractor and its load increases above and beyond what is required for good ground floatation practice. The key point is that a balance must be reached.

As a rule of thumb, modern tractor tyres should have between three or four lugs on the ground.


Keep that image of three or four lugs touching the ground in your mind's eye.

Radial tyre technology has developed hugely. Twenty years ago the neighbour could have accused you of running on a flat if he saw four lugs on the ground.

However, nowadays that kind of tyre deflation is encouraged for good soil husbandry. To have three or four lugs on the ground at any given time on the rear tyre of a typical 180hp tractor the pressure should be just over 1 Bar – in old money that is 17psi.

Contractors and farmers should check tyre pressure once a week at all times of the year but especially at this busy time in the fields.

If your load is going to change significantly for a certain week, using a large slurry tanker for example, then you should alter pressure as appropriate. Equally, if you are doing nearly all road work, the same applies – you can put a bit more pressure in there.

The other area to keep an eye on is ballasting that is no longer required.

It is common to see plenty of tractors being driven around with unnecessary weight boxes or ballasts still in tow long after the winter months have passed.

For those lifting bales this is obviously still necessary, but for farmers who no longer need the added weight, it is madness. Table 1 shows the average litres per hectare of fuel usage for some common spring jobs.

Don't add to that usage for the sake of the few minutes it takes to remove any excess baggage from the tractor.

Irish Independent