Savings in fuel use of between five and 30% can be achieved by simply selecting the right tractor tyre pressure or appropriate tyre size, according to recent on-farm trials by Firestone as part of the EU-wide Efficient 20 fuel saver programme.

At around 70ppl for red diesel, that’s a saving worth at least 3.5ppl and as much as 21ppl, which no farm business can afford to ignore, points out Firestone’s farm tyre product manager Barrie Coleman.

“We’re all conscious of rising fuel bills but some of the inefficiencies can be removed by simply getting tyre pressure right for the relevant operation or task.”

Practical trials conducted in late September at John Lewis’s 400ha (1,000-acre) organic unit in south Shropshire as part of an EU-wide project called Efficient 20 – aimed at finding ways to improve fuel efficiency in farming by 20% – showed how savings could be made.

The farm’s 8,000-hour John Deere 6910 tractor coupled with a five-furrow Dowdeswell plough was put to work turning over loam soil in preparation for drilling. Using GPS monitoring and a retro-fitted digital fuel flow meter, Mr Lewis’ progress was recorded and converted into fuel use/ha using an iPhone App developed by Mr Coleman and Rob Mannion, managing director of trials co-ordinator Ruralnet Futures, whom also oversees the Efficient 20 project.

“Having spoken to farmers at a number of meetings in the past, we initially set the tyre pressure at what many believe is about right with both front and rear tyres at 23psi,” explained Mr Coleman (see table). “Before we set off for the field the tractor and plough was placed on weigh cells with the implement in both transport and work position.”

In-field monitoring over a 30-minute ploughing session showed fuel use fell by 5% when tyre pressure was switched from assumed to actual best operating pressure (down from 23psi all round to 14psi up front and 17psi in the rears). “That’s in line with our expectation,” said Mr Coleman.

Watch a video of the test

For Mr Lewis, a 5% saving on the 25,000 litre annual red diesel usage would equate to about 1,250 litres or approximately £875 at 70ppl. “It’s quite an eye-opener seeing how just altering tyre pressure can make a difference,” reflected Mr Lewis. “Any saving in fuel use and cost is welcome as it just seems to go up year-on-year.”

But significantly larger savings could be made. Switching the tractor tyres to a wider footprint for cultivation work would potentially reduce wheel slip thereby saving fuel, explained Mr Coleman. “Ideally the front axle should carry 40% of the load when an implement is in work position.

“That does require operators to have access to a weighbridge that can measure loads on a per-axle basis but it is key information if fuel efficiency is to be maximised.

“Tyre pressure is still important, as the in-field testing showed. When run over-inflated, the wider tyres delivered an improvement in fuel use but nowhere near that achieved when set correctly. The combination of correct pressure and correct tyre size resulted in a 30% saving in fuel use which, for Mr Lewis, was quite a surprise,” explained Mr Coleman.

Indeed, had Mr Lewis not checked the digital readout in the 6910’s cab himself he would not have believed that fuel use on over-inflated original tyres of 12.28 litre/ha had fallen to just 8.09 litre/ha with wider correctly inflated tyres – a saving of about 30%.

To get near these savings in fuel use, farmers need to get tyre savvy but also manufacturers need to work harder to educate tyre users on selecting the most appropriate tyre size for a machine’s use, says Mr Coleman. “It’s quite understandable to assume that the right tyre for a tractor is the one it came with, but it is dependent on what you do with the tractor that matters.

Ruralnet Futures will be conducting more on-farm testing at various locations across the UK as part of the six-year Efficient 20 programme.