<p>This study investigated the effect of tire crumb and bitumen on soil shear-strength parameters. Used tire crumbs are components of tire factory waste that can be incorporated into the soil and buried in construction projects. Therefore, this process is environmentally and economically beneficial. The current study was performed in three modes, A, B, and C. In the A mode, soil was reinforced by tire crumb, in the B mode, it was reinforced with bitumen, and in the C mode, it was reinforced with tire crumb and bitumen. These tests showed that the shear-strength parameter increased by adding crumb rubber to the soil. When the amount of tire crumb reached 2%, shear strength reached its peak value. By adding 2% of tire crumb to the soil, the shear-strength parameter increased to 17%. The shear strength of the soil, which was reinforced by the addition of 10% of tire crumb, was approximately equal to the shear strength of the unreinforced soil. In addition, the presence of tire crumb in the mixture leads to a reduction in the specific gravity of the samples. Also, bitumen decreased the friction angle and increased the cohesion of the soil.</p>