Although soybean oil (SBO) has been successfully used as a bio-based, renewable processing oil (PO) for rubber compounds, SBO can impart very different properties as compared to conventional petroleum-based POs. For example, direct replacement of a commercial aromatic PO with SBO in a carbon black (CB)-filled styrene butadiene rubber (SBR) resulted in significantly reduced mechanical properties. As a result, chemical modification of SBO was investigated as a means to overcome rubber compound property deficiencies. Three different chemical modifications were investigated, namely, conversion to a polymer, conversion to sucrose octasoyate, and styrenation. Conversion to a polymer involved the production of a vinyl ether monomer from methyl soyate and subsequent cationic polymerization. Conversion to sucrose octasoyate involved base-catalyzed transesterification of sucrose with methyl soyate, and styrenation involved free-radical grafting of styrene to SBO. When these different modified SBO compounds were used as POs in CB-filled SBR, many of the properties that were deficient with respect to the control rubber based on the petroleum-based PO were enhanced. In fact, some of the modified SBO materials provided rubber properties that were very similar or better than the control. Based on the type of SBO modification, viscoelastic and mechanical properties could be tailored over a fairly wide-range. Of particular interest was the much better balance between predicted wet traction performance and predicted rolling resistance that could be achieved with many of the SBO-based compounds.