27 September 1996

Low profile radial gives loads of traction

SUBSTANTIAL improvements in traction and floatation are claimed for Klebers latest radial tractor tyre, the ultra-low profile (65-series) Super 11L, when used to replace typical standard fitments on 100hp+ tractors.

The low sidewall/wide tread design of the tyre allows it to replace standard tyres without having to invest in new wheels, making it an economical route to improved tractor performance, says Kleber.

"Tests at our research and development centre in France have shown up to 40% more traction, 25% less soil compaction and up to 50% increased tyre life can be gained from switching to the wider tyres," says Kleber technical manager Ed Rainbow. "The tyres also have some 20% more load capacity at a given pressure, so they can carry more, or carry the same load at lower inflation."

Six sizes will be available initially (see table) for front and rear-wheel mounting on four-wheel-drive tractors up to 180hp; further sizes will be introduced in due course.

Compared with existing Kleber designs, the Super 11L has more distinctly squared-off shoulders, and curved lugs set at a slightly shallower angle to combine good wear and vibration characteristics on the road, as well as good traction in the field.

Klebers distinctive "inter lugs" are retained – they help with self-cleaning characteristics as well affording some tread protection – while block mouldings provide sidewall protection without detracting from the flexibility that enables the tyre to present as big a contact patch as possible under load.

A like-for-like comparison of the 600/65R38 Super 11L with the 18.4R38 Super 9 it can replace shows the gains made with the bigger tyre.

Fitted on a typical 130hp tractor carrying a five-furrow mounted plough, the smaller tyre would need to be inflated to 1.65 bar (24psi) to carry the 3380kg (7451lb) a tyre load, while the larger replacement would need only 1.17 bar (17psi).

The increased load carrying capacity comes from a combination of the new tyres structure and its larger volume – the 600/65R38 contains 34% more air than its smaller equivalent. The likely improvement in traction and flotation, meanwhile, is illustrated by measurement of the contact patch of the two tyres in this situation – 3355sq cm (520sq in) for the 65-series tyre as against the 80-series tyres 2632sq cm (408sq in).

Comparison of standard with latest radial tyres for 100hp+ tractors

StandardSuper 11LIncreased

80-series65-seriestread width*

14.9R24480/65R24100mm (4in)

14.9R28480/65R28100mm (4in)

16.9R24540/65R24210mm (8.75in)

16.9R28540/65R28210mm (8.75in)

18.4R38600/65R38130mm (5in)

20.8R38650/65R38120mm (4.75in)

* Approximate figures; increased contact patch width and length will result from being able to operate the wider tyres at lower inflation pressures for the same load.

Klebers technical manager, Ed Rainbow with his companys new ultra low-profile radial tyre: "Forty % more traction, 25% less soil compaction and up to 50% increased life," he says.