Soil response to differences in tire size and inflation pressure was measured for a JD 9600 combine with 18.4R38 dual tires, 30.5L32 single tires, 68x50.00-32 single tires at 103 and 166 kPa inflation pressure and a John Deere half-track system on two different soils (Kokomo and Crosby) near Urbana, Ohio. A loaded 42.3 m3 grain cart was included on the Kokomo soil for comparative purposes. The Ohio State Soil Physical Properties Measurement System was used to sample and measure the bulk density, air-filled porosity, air permeability and cone penetration resistance between 10 and 50 cm depths. The results for Kokomo soil show the grain cart had the greatest effect with an average decrease in total porosity of 12.90 percent, compared to 7.95%, 6.05%, 4.56%, 3.06%, and 2.04% for singles, tracks, duals, wide overinflated, and wide rated pressure tires, respectively, on the combine. The average increase in dry density was 12.00% for the grain cart compared to 6.19%, 4.99%, 3.09%, 2.26%, and 1.20% for singles, tracks, duals, wide overinflated, and wide rated pressure tires, respectively. The average decrease in air permeability was 89.47%, 79.81%, 71.72%, 61.49%, 57.42%, and 48.34% for the grain cart, singles, tracks, duals, wide overinflated, and correctly inflated tires, respectively. The results for Crosby soil showed the same trend but different percentages. In general, the results were consistent across treatments at each depth.