The size and weight of agricultural tractors and machinery have increased in recent years, resulting in increased soil compaction. As a consequence, aeration, root growth and infiltration rate are impeded. Field studies were conducted and soil compaction variables were measured beneath the rear tire track of a two-wheel drive tractor operating with zero drawbar pull. The dynamic load on each rear tire was varied from 7.27 to 13.50 kN and the forward velocity was varied from 0.78 to 2.5 m/s. To determine so soil compaction, the cone index, bulk density, shear strength and tire sinkage were measured. The results showed that increasing the tire load at a given forward velocity increased the cone index, bulk density, shear strength and sinkage. Tire load affected cone index, bulk density, shear strength and sinkage more strongly than did forward velocity. © 1994.