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United States Department of Agriculture

Agricultural Research Service

Title: Soil-Tire Interface Pressures of a Low Aspect Ratio Tractor Tire

Authors
item Way, Thomas
item Kishimoto, T - OBIHIRO UNIV., JAPAN
item Burt, E - RETIRED ARS
item Bailey, Alvin

Submitted to: Book Chapter
Publication Type: Book / Chapter
Publication Acceptance Date: January 5, 2000
Publication Date: March 5, 2000
Citation: Way, T.R., Kishimoto, T., Burt, E.C., Bailey, A.C. 2000. Soil-tire interface pressures of a low aspect ratio tractor tire. In: Horn, R., van den Akker, J.J.H., and Arvidsson, J., editors. Subsoil Compaction: Distribution, Processes and Consequences. Advances in GeoEcology 32. Reiskirchen, Germany: Catena Verlag GMBH. p. 82-92.

Interpretive Summary: Soil compaction prevents crop roots from reaching more soil to access water and nutrients, reduces infiltration of water into soil, and increases soil erosion. Farming systems will become more sustainable and the environment will improve if undesirable soil compaction is reduced. Agricultural producers and designers of agricultural tires and vehicles can reduce soil compaction if they have information about impacts of tires on compaction. Researchers investigated effects of the weight supported by tires and tire air pressure, on contact pressures applied to soil by tires and on soil compaction. Contact pressures of a radial-ply tractor drive tire were measured on a sandy loam soil. When radial-ply tractor tires are inflated to the air pressure recommended for a particular load, the tire sidewalls bulge and this has caused many users to increase the air pressure to reduce the bulge. Use of air pressures greater than the pressure needed for a particular load, however, was found to increase contact pressures at the soil-tire interface and to cause increased compaction of soil beneath the tire. To minimize soil compaction and maximize efficiency without damaging tires, users should set air pressures of radial-ply tractor tires to the pressures recommended by the tire manufacturer for the particular loads supported by the tires.

Technical Abstract: A 580/70R38 radial-ply tractor drive tire was operated at two dynamic loads and two inflation pressures at 10% travel reduction on a sandy loam with loose soil above a hardpan. Soil-tire interface pressures on the face of a lug were measured as the lug passed through each soil-tire contact patch. The interface pressures were concentrated more at the middle of the lug and at the edge of the tread than near the centerline of the tire when the tire inflation pressure was 40 kPa and the corresponding correct load was used. When the inflation pressure was 120 kPa and the corresponding correct load was used, the interface pressures were distributed more uniformly among the three locations on the lug. Overinflation caused the middle of the lug and the tire centerline to have relatively high interface pressures, and caused the length of the footprint and the footprint area to be relatively small. When the tire was underinflated, the greater interface pressures were concentrated at the edge of the tread, and the length of the footprint and the footprint area were relatively large. Distributions of soil- tire interface pressures on lugs of a radial-ply tractor drive tire on loose soil are more uniform if the tire is operated at a combination of dynamic load and inflation pressure recommended by the manufacturer than if the tire is overinflated or underinflated.

Last Modified: 7/24/2014
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