The technological aspects of polymer processing are very closely related to rheological behavior, because the most processing technologies of polymeric materials are based on the processing of these materials in the melt, where the polymer flow occurs, resp. to polymer deformations. The rheological behaviours were evaluated on rubber process analyzer by tests of strain sweep, frequency sweep. The rubber process analyzer is a dynamic mechanical rheological tester, and it is universally used for characterizing raw elastomers and uncured blends. The blending of different elastomers and their compatibility, the dispersion of fillers in polymer matrices and compatibility between filler and elastomers are the major topics for application of the RPA in relation to elastomers. The presented paper is focused on the effect of alternative fillers on the rheological behaviours of polymer blends. The selected alternative fillers were used as a partial replacement for the commercially used active filler - carbon black N339 in the tread blend. From the measured results of the rheological behavior for the tested samples, we can state that even a small amount of alternative filler affects the resulting properties of polymer materials. This research work has been supported by the Operational Programme Integrated Infrastructure, co-financed by the European Regional Development Fund by the project: Advancement and support of R&D for "Centre for diagnostics and quality testing of materials" in the domains of the RIS3 SK specialization, Acronym: CEDITEK II., ITMS2014+ code 313011W442.