Constant growth of waste polymers around the world leads to several environmental problems. This is why solutions to re-use these high amounts of materials available must be developed. In this work, highly filled (up to 90 wt.%) recycled polyethylene (R-PE)/ground tire rubber (GTR) thermoplastic elastomers were prepared by extrusion compounding and injection molding. To improve on processability and overall properties, two copolymers (Engage 8180 and Vestenamer 8012) were added as compatibilizers for comparison. SEM results showed that compatibilizer addition changed the blend morphology. In all cases, the mechanical properties in tension and flexion decreased with GTR addition. It was also observed that the addition of a copolymer improved on some properties (such as elongation at break), but Engage 8180 showed better compatibilization effect than Vestenamer 8012 which was confirmed from SEM analysis, while other properties (tensile strength, Young's and flexural modulus) were reduced due to lower GTR and compatibilizer moduli. For impact strength, negligible variation was observed below 40 wt.% GTR. However, the samples did not break for GTR contents above 60 wt.%. Density increased with GTR content, while Shore A and D hardness decreased. Overall, the addition of a compatibilizer mostly enabled to produce compounds at higher GTR contents (above 70 wt.%). From the result obtained, it can be concluded that recycled materials can be used to produce blends with reasonable quality for automotive, packaging and construction applications since the mechanical properties can be optimized via formulation over a very wide range of GTR (0-90 wt.%).