Abstract— Different artificial materials including waste rubbers have been used to improve soil properties for construction purposes. This study evaluates the effect of reinforcement with waste tires on the shear strength of sands. For this purpose, a series of direct shear tests have been performed on a sandy soil reinforced with different forms of waste tires. Increase in the percentage of the shredded tires resulted in an increase in the optimum water content and a decrease in the unit weight of specimens. The results of the direct shear tests show an improvement in the shear strength of reinforced soil samples than unreinforced soils. In addition, a 7% higher mobilized shear strength of the reinforced samples with fiber shredded tires compared to the reinforced samples with sheet shredded tires supports the influence of the forms of waste tires on the shear strength of reinforced soil.