Design optimisation and greatly reduced development times have resulted from the implementation of finite element analysis in automotive component manufacture. Rubber component design has remained an exception to this trend due to poor material models inadequately representing hyperelastic and viscoelastic behaviour. However, with a clear understanding of working environment and an appropriate choice of material constants we have the ability to sensibly predict elastomeric deformation and thus make well designed rubber products economically. This paper compares the results from plane strain indentation tests on hydrogenated acrylonitrile butadiene rubbers (HNBRs) of different hardness with finite element analyses employing a variety of material models having material constants derived from tests conducted over a range of feed rates. The influence of indentor surface finish, lubrication, stress relaxation and adhesion between indentor and rubber has also been examined and these results await publication. The plane strain test-pieces were deformed by indentors having half-cylinder edge profiles allowing their finite element representation as rigid continua. Video microscopy was used to observe both the indentation and stress relaxation phase of each test. Because there were combinations of surface finishes, feed rates and hardness, mechanical conditioning (scragging) of the test-pieces was not feasible. However, the standard tests employed to provide data for finding material constants used unconditioned samples, so comparisons are valid. Regression analysis to determine material models from standard tests, improved finite element analysis and an evaluation of competing strain energy density functions are discussed. However, the principal focus of this text is an evaluation of the choice of material constants when nitrile rubbers and metal surfaces are brought into contact. It is shown that, despite the variation in material constants with different feed rates and the competing claims of alternative strain energy functions, design engineers can define material models that allow confidence in hyperelastic finite element analysis.