Non-petroleum based oils replace traditional process oils used in rubber compositions in general and specifically in footwear applications. The replacement oils, derived from plant or animal sources, represent a renewable resource and provide other advantages. The oils contain a sufficient level and distribution of fatty acid side chains to partially incorporate into the rubber at low levels, and to act as internal plasticizers at higher levels. Other compositions are free of silane coupling agents and additives that generate carcinogenic nitrosamines.