A shape factor based non-linear model of a rubber cylinder's temperature and preload dependent static stiffness is presented. The influence of temperature, precompression, material parameters, cylinder length and diameter, are investigated; with the motion split into a homogeneous thermal expansion including a globally equivalent preload deformation. Stiffness depends strongly on preload, particularly in larger shape factors, and on temperature. The model proves superior to traditional work in typical shape factors, with results close to those of finite element models.