Investigating the effect of velocity, inflation pressure, and vertical load on rolling resistance of a radial ply tire

A single-wheel tester facility at Department of Agricultural Machinery of Urmia University was utilized to investigate the effect of velocity, tire inflation pressure, and vertical load on rolling resistance of wheel. A Good year 9.5L-14, 6 radial ply tire was used as the tester wheel on clay-loam soil and was installed on a carriage traversing the length of soil bin. Three inflation pressures of 100, 200, and 300 kPa as well as three levels of velocity (i.e. 0.7, 1.4, and 2 m/s) and five levels of vertical load applied on wheel (i.e. 1, 2, 3, 4, and 5 kN) were examined. Covariance analysis (ANCOVA) of resulted data revealed that rolling resistance is less effected by applicable velocities of tractors in farmlands but is much influenced by inflation pressure and vertical load. An approximate constant relationship existed between velocity and rolling resistance indicating that rolling resistance is not a function of velocity particularly in lower ones. Moreover, it was observed that increase of inflation pressure results in decrease of rolling resistance. Additionally, increase of vertical load brings about increase of rolling resistance which was estimated to have polynomial relation with order of two. A model comprising tested variables was developed with relative high accuracy.