Archive Article: 1997/10/18
AVOIDING soil compaction is the driving force for most UK purchases of dual wheel systems and clamps, but users should watch tyre pressures to get the most from their wheels.
The temptation is to run the tractor tyres at road pressures and drive straight into the field and start work without altering those pressures.
"Most tyre failures are caused by incorrect inflation and the wrong applications," says Paul Johnson, of dual wheel importer, Terry Johnson.
"Pressures will depend on what you are doing with the tractor and what the tyres will take. It is important to stick to the main tyre pressure recommendations from the tyre manufacturers."
However, Mr Johnson highlights another common oversight by users who inflate tyres on dual wheels to equal pressures. "You dont want equal pressures because of the strains they put on axles which can cause problems particularly for some of the new four-wheel drive machines where the axles camber right over."
Johnsons recommend the outer wheel in the pair should be inflated only to 75% of the pressure in the main tractor wheel to reduce these strains.
However, it is a mistake to run those tractors in the field at road pressures, says Mr Johnson. Users will get better flotation and traction from properly adjusted tyres. Go too low and there is a risk of the tyre spinning on the wheel rim.
Mr Johnson, who imports dual wheel components made by Schaad Brothers of Switzerland, says users should look for clamps with a short hitch arrangement which are easier to fit. He suggests two clamps are sufficient for tractors up to 120hp, three for the 120 to 160hp machines, and four clamps per wheel for bigger equipment up to 200hp.
Users should also take into account whether they will be working downhill frequently with dual wheels where the wrong choice of clamp could result in wheels loosening. Most UK users opt for equal size wheels and tyres but using narrow row crop wheels could fit into systems using 3m drill/harrow combinations.