Emulsion polymerized compression molded dicumyl‐peroxide‐cured SBR does not obey Boltzmann's principle for the superposition of time effects at very small strains at which the true stress‐strain relation is linear. Normally, nonpreservation of time shift invariance is linked with stress‐strain nonlinearity. In this anomalous styrene‐butadiene rubber (SBR) the former effect can be studied independently of the latter.