The necessity to repurpose End-of-Life Tires (ELTs) has driven researchers to seek new methods for converting them into useful products. Recently, shredded rubber from ELTs has been increasingly utilised in various civil engineering fields due to its valuable mechanical properties. Over the past few years, numerous experimental tests have been conducted on the use of shredded scrap tyres mixed with poorly-graded granular soil, primarily sand or gravel, as backfill material for retaining walls, liquefaction mitigation, structural fill, and geotechnical seismic isolation (GSI). Many studies in literature have focused on the mechanical properties of sand-rubber mixtures, while limited research has been done on the behaviour of gravel-rubber mixtures. This paper aims to explore the physical and mechanical properties of more economic and easy-to-prepare geomaterials combining well-graded gravel mixed with scrap rubber grains (wgGRMs) through isotropically consolidated drained monotonic and cyclic triaxial (TxCD and CLTxT) tests. The tests were carried out by varying the confining pressure and the volumetric rubber content (VRC). The results highlight the effect of confining pressure and VRC on the stress-strain relationship and volumetric and cyclic behaviour.