<p>Laboratory pullout tests were performed to examine the pullout behavior of flexible geocells constructed from waste tires embedded in sand, focusing on deformation properties, group interaction effects, and pullout resistance prediction. Model tire geocells with 1 × 3, 2 × 3, and 3 × 3 configurations were subjected to normal stresses of 25, 50, 75, and 100&#xa0;kPa, and a 4 × 3 configuration was utilized for validation. The findings revealed that increased normal stress and a greater number of geocell units led to higher maximum pullout force. At a normal stress of 100&#xa0;kPa, altering the configuration from 1 × 3 to 3 × 3 elevated the maximum pullout force from 1.26 to 2.22 kN, reflecting an increase of 76.2%. The normalized pullout force decreased from 40.4 to 23.7 kN/m², suggesting a significant group interaction effect. Front- and rear-end displacement measurements revealed that the pullout process comprised three stages: Deformation, deformation-sliding, and sliding. At the same normal stress, the critical displacements for the transitions to the deformation-sliding and sliding stages in the 3 × 3 configuration were 100% and 42.8% higher, respectively, than those in the 1 × 3 configuration. An analytical model was proposed by decomposing the maximum pullout resistance into frontal resistance, sidewall friction, and interface friction at the upper and lower surfaces based on this mechanism. Validation utilizing the 4 × 3 configuration revealed that the predictions accurately reflected the experimentally observed variation within the tested normal-stress range and yielded conservative estimates, suggesting that the model is reasonably accurate for tire geocell design.</p>