Soil compaction can cause significant crop yield reductions. Effective management of soil compaction caused by tractors requires an understanding of the influence of the tractive system on soil compaction. Soil strain under tractors equipped with single rear wheels, dual rear wheels, or steel tracks was measured and compared. Tractors were of nearly equal mass. Strain was measured by using soil-strain transducers installed at 100-, 150-, 200-, and 300-mm depths beneath the soil surface. Soil strain was defined as the change in transducer length divided by the initial length of the transducer when installed in the soil. Soil strain at 100- to 245-mm depth was significantly greater for the tractor with single rear wheels than for the other tractors. The difference in soil strain caused by tractors with different tractive systems decreased with soil depth.