Not sure what pressure your tractor tyres should have in them? Confused by the tricky business of looking through endless technical data sheets to find out? You’re in good company, with only a small minority of farmers reckoned to know how to set the inflation pressure correctly.

But tyre giant Bridgestone/Firestone reckons it has the answer. It now has an app that can be downloaded onto your iPhone that will to do the job for you in seconds.

What’s an app? It’s small bit of software that sits on your phone and does a specific task very quickly and simply, whether it’s calculating how long it’ll take to drive to Carlisle or listing all the flight arrivals at Heathrow on any particular day.

Six months ago there were no farming apps, but there are now ones that calculate tank mixes, tell you today’s wheat price and work out sowing rates instantly. And the arrival of Firestone’s tyre pressure calculator is reckoned to the first one to tell you what pressure you should be putting in your tractor tyres.

It’s sorely needed, admits Firestone’s product manager Barry Coleman. “In the past, when farmers wanted to know what tyre pressure they should run at, tractor and tyre manufacturers have tended to say “go and have a look at the technical data book”.

“But very few farmers would have one of those and they’re complicated to use. Finding that information on tyre makers’ websites has often been very difficult, too,” says Mr Coleman.

“Yet getting your tyre pressures right is one of the most important things you can do,” he adds. “If you get it wrong, you’re causing a lot more ground compaction, you’re using more fuel and you’re wearing out the tyres prematurely.”

Over-pumped-up tyres are the chief culprit, he says, with farmers often nervous about the sight of a bulge at the bottom of a modern radial tyre and inclined to put in more air than is needed. Routine tyre over-inflation of about 40% is quite common, says Mr Coleman.

So how does the new, free, Firestone TPC (tyre pressure calculator) app sort all this out? Here are the steps involved:

• Bring up the app on your phone and look up the tyres you have. If they’re Firestone ones, the exact name and size will appear. But the app will work almost as well with any other make of tyre.

• Now look at the data plate at the back of the tractor (usually just below the back window). It will quote maximum loadings for each axle, giving a range. So for a front axle it might say 1,900-4,100kg

• Divide that by two, so you have a max weight for each tyre.

• Decide what your max speed is (eg, 10kph for fieldwork or maybe 50kph for roadwork)

• Now the app will give you a recommended tyre pressure in bar.

• If you want to know the name address and directions to the nearest Firestone agricultural tyre dealer, it will also give you that, too.

At the moment, the Firestone TPC can only be downloaded on to an iPhone, but a version for smartphones that use the Android operating system will be available soon. If you haven’t got either of those, you can still access the data sheets on the Firestone website.