Tyre giant Michelin claims its latest combine tyre could make it it less stressful for farmers and contractors to take harvesters on the road.

Developed jointly with Claas, the Michelin CerexBib is 15% narrower than any conventional harvester tyre. This means manufacturers can build larger combines without exceeding a width of 3.5m, the threshold at which EU regulations stipulate that harvesters require special order movements from the police (as well as on-road escorts).

Michelin says the ultra-flexible CerexBib tyre is the only commercially available tyre that can work at a pressure of less than 2 bar (29psi). This is about 30% less than conventional tyres.

A Michelin CerexBib IF* 680/85 R 32 – one of four sizes available from launch – has the same load capacity as the 800/70 R 32, yet benefits from a footprint which is 20% larger thanks to more flexible sidewalls.

This increases the opportunities to harvest, even in damp soil conditions, because the low operating pressure of just 1.6 bar (23psi) ensures that soil compaction is reduced.

“Compared to a conventional tyre, CerexBib offers an additional 20% load capacity for the same pressure, whilst the reduced tyre width solves a major headache when transporting combines between fields,” says.

Rob Beddis, commercial director of Michelin’s UK and ROI agricultural division.

Tom Pine, Claas UK combine product manager, adds: “For example the new Lexion 750 is already available to order with 680/85 R32 CerexBib tyres. These reduce the overall vehicle width to 3.3m, whilst still delivering a 12%t larger footprint than the normal 800/65 R32 tyre.”

The CerexBib can be used on both the front and rear axles of combines and can climb slopes of up to 24%, compared with 19% for a conventional harvester tyre).

The larger contact patch and lower ground pressure reduce rut depth and increase traction on wet and dry soil, adds Michelin, saving farmers time and cutting fuel use. The flexible sidewalls also increase ride comfort.

Even at low operating pressures, the CerexBib is said to give better stability, improved steering response and less vibration and noise.

The Michelin CerexBib is initially available just on the Claas Lexion range of combine harvesters but will be launched on to the European replacement tyre market in 2011. Sizes include the IF 680/85 R 32, VF 520/80 R 26, IF 800/70 R 32 and VF 620/70 R 26. A further six sizes are in development and will be available at the end of 2011.