Mass production of tires and their subsequent storage after use are serious environmental problems that are being tried to be solved in various ways. One of these is the mixture of these old used tires [ground rubber tire (GTR)] with various thermoplastic and thermostable polymers. The present work aimed to obtain materials suitable for the electric industry from the mixture of polystyrene (PS) with old used tires (GTR), starting from the requirement of minimum recycling costs, i.e., by using vulcanized GTR without any prior treatment but acting on the particle sizes with a simple and inexpensive screening. In order to do so, dielectric, mechanical, thermal, and microstructure analyses were performed for a large number of compounds, which were obtained using three GTR particle sizes (p<200 μm, 200 μm500 μm) and seven concentrations of GTR in the compound (0%, 5%, 10%, 20%, 40%, 50%, and 70%). All these data have allowed an accurate characterization of the properties of the new compounds, and according to these results, possible electrical applications have been explored.