The latest range of tractor tyres from Michelin aims to give higher work speeds, better driver comfort and fewer ruts. The Michelin Series 70 Omnibib are targeted at tractors from 70-180hp, typically operated by mixed farmers.

Some 60mm wider than the equivalent 85 series tyre, and generally able to be fitted to the same rims, the new tyres are designed to be run at lower pressures. That brings several benefits, says the company.

First off, it gives a smoother ride for drivers, so tractors can be driven faster in comfort. At the same time the new tyre has wider, more tapered lugs to boost both traction and self-cleaning ability.

A bigger footprint means less chance of creating ruts, too. Of the compaction that a tractor generates in any particular field, 80% comes the first time it heads down the tramlines, says Michelin’s head of tyre marketing Lionel Matrat.

“The soil is wet and the farmer is in a hurry,” he says. “But that deeper rut means the sprayer bounces more when it crosses it, the combine has to slow down and that rutted area will also be tougher to plough in the autumn.”

The extra width of the Omnibib also means reduced wheelslip – Michelin reckons 2% less. That may not sound a lot, but over any substantial acreage it adds up.

“If you are ploughing 150ha with a 150hp tractor and five-furrow plough you will actually travel 728km,” says Mr Matrat.

“So if you reduce slip by 2%, you will plough 3ha more in the same time. That’s two-and-a-half hours saved.” That also means less fuel used.

The new tyre is also aimed farmers running front loaders. As loads get heavier, says Mr Matrat, farmers often compensate by fitting relatively skinny (and bump-prone) front tyres running at high pressures. The wider Omnibib, he says, is better matched to modern loadings and will make the ride a lot less bumpy.

Most of the more common sizes of Omnibib will be available from this month, while other sizes will go on sale in early 2009. They are expected to cost about 10% more than the equivalent 85 series tyre.