Michelin’s novel EvoBib tractor tyre, designed to adapt its carcass and tread pattern at different inflation pressures, has been given a structural makeover to further improve its performance.

The EvoBib is purpose-designed for tractors with a central tyre inflation system (CTIS) carrying out a broad range of road transport and field duties.

See also: Central tyre inflation systems – the options and prices

Michelin acknowledges that if 80% or more of the work is in the field, especially in challenging conditions, its AxioBib 2 VF design will be a better bet.

Likewise, the transport-oriented RoadBib is the best option if the tractor spends 80% or more of its time on tarmac because of its longevity and fuel economy advantages.

But between those extremes, say Michelin engineers, the EvoBib offers attractive performance characteristics on the road and in the field due to its adaptive design.

New-generation EvoBib is said to deliver improved on-road and in-field performance © Michelin

Hybrid lugs

The tyre has a so-called hybrid lug pattern with different-sized and -shaped blocks arranged in a traditional format with a discontinuous rib down the centre.

The carcass incorporates the Ultraflex technology that allows a supple sidewall on Michelin’s IF and VF tyres.

At road-going pressures, the tyre has a smaller footprint and relies more on the central rib of the tread pattern to cut rolling resistance and ease fuel consumption.

Using a CTIS package to quickly lower the inflation pressure for field operations extends the contact patch lengthways and sideways for maximum traction and flotation characteristics.

Michelin says the tyre can vary the size of its footprint by 47% – double that of a VF tyre such as the AxioBib 2 – and, in comparison tests, is reported to have delivered the same in-field traction as a VF tyre with regular lug pattern tread.

In fuel consumption trials, the EvoBib is said to compare favourably with alternative tyres.

Just one combination of sizes is available for the time being – a VF 710/70 R42 and VF 600/70 R30 – for use with tractors of 200-300hp with CTIS, but further sizes should be introduced this year for larger tractors of more than 300hp.