In this study, Aspen Plus V12® was used to model and simulate the pyrolysis and co-pyrolysis processes of date seeds and tire plastic waste to analyse the performance of these feedstock blends in bio-oil, biochar, and syngas production yields. The results of this analysis were further processed in the software RSM Design Expert 12 to investigate the interactions among temperature, pressure, and blending ratio. The results obtained in this paper show that regardless of the reaction temperature and pressure, bio-oil yields are influenced mainly by the tire plastic-to-date seeds blending ratio. The lowest bio-oil yields (67–72 kg/h) were obtained when only date seeds were pyrolyzed, while the highest bio-oil yields (254–286 kg/h) were obtained when only tire plastic was pyrolyzed. However, when only tire plastic was pyrolyzed, biochar yields were the lowest (246–264 kg/h). Conversely, the highest biochar yields (264–592 kg/h) were achieved when only date seeds were pyrolyzed, regardless of the reaction temperature and pressure. The highest syngas yields (428–486 kg/h) were obtained when only tire plastic was pyrolyzed, at different reaction temperatures and pressures; the lowest syngas yield (284 kg/h) was obtained when the tire plastic-to-date seeds blending ratio was 50%. Statistically significant correlations were found between bio-oil and biochar yields and the tire plastic-to-date seeds blending ratio. These results show the suitability of co-pyrolysis of date seeds and tire plastic waste for bio-oil, biochar, and syngas production, which can be used simultaneously as a waste management strategy and as an alternative biofuel feedstock for the transportation, heating, cooling, and electricity sectors. This blending also improves the circularity of biofuel production by repurposing end-of-life plastic waste that would otherwise be land-filled. © The Author(s), under exclusive licence to Springer Nature Switzerland AG 2025.