Larger, more powerful tractors are the target for Bridgestone’s latest farm tyre additions – XXL versions of the VT-Tractor radials in 44in and 46in rim sizes with corresponding 38in and 42in front fitments.

The VT-Tractor is a very high-flexion (VF) category design capable of operating at significantly lower inflation pressures than a “conventional” tyre of the same size carrying the same load.

Conversely, it can carry heavier loads at the same inflation pressure, so operators have a choice of how they benefit from opting for the more advanced construction of a VF tyre.

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Bridgestone has a well-established collection of VT-Tractor sizes, covering 28in to 42in rim sizes from the VF 480/65 R28 to the VF 900/50 R42.

Of the six additions, the VF 650/60 R38 is now the lowest-profile “650” in the 38in rim size, the VF 650/85 R42 is a taller and larger volume “650” among the 42in tyres, and the VF 800/70 R42 is an altogether new size for the range.

XXLs arrive

The trio of VF-Tractor XXL sizes, meanwhile, are the VF 750/70 R44, VF 750/75 R46 and VF 900/65 R46, which have required investment in larger moulds and other manufacturing facilities at Bridgestone’s Puente San Miguel plant on the coast of northern Spain.

Features include deeper lugs – 59mm on the VF 650/60 R38 and 66mm on the VF 750/70 R44 – for added traction and a greater service life.

The lugs are also involute or “bulging” in cross-section – a bit like the shape of gear teeth – for a total rubber volume up to 12% greater than leading competitor tyres. This contributes to long-term durability by regulating deformation under load and “flick” as the lug emerges from the soil.

The stability of Bridgestone’s S-Line bead profile is said to allow greater sidewall flexibility at low inflation pressures while still preventing rim slip under heavy traction loads.

The company’s engineers also say they have focused on ensuring the optimum lead percentage between matched front and rear tyre pairings to minimise strain on tractor driveline components.