<b>Abstract</b>— <p>The influence of chemical composition and structural characteristics of elastomer mixtures on the mechanical properties of vulcanizates obtained on the basis of styrene ethylene-propylene butadiene-nitrile rubber (SKEP-BNK) is studied. The main attention is paid to the influence of the polydiene rubber (PD)- and dithiobis-maleimides (DTBFM) concentration on the strength properties, resistance to thermal-oxidative aging, and fatigue endurance of vulcanizates. The results of experimental work related to the change in mechanical properties depending on the variation of concentrations of these components in the mixture are presented. Possible mechanisms for improving the properties of vulcanizates under the influence of external factors are discussed.</p>