Although the volume of research on carbon nanotubes (CNTs) has increased over a short period, less attention has been paid to other types of carbon-based nano-objects such as boron carbide (BC 3) nanotubes (BC 3 NTs). In the present article, we modeled BC 3 NTs using molecular dynamics (MD) simulation to investigate the effects of chirality, wall number, diameter and temperature on the mechanical failure of BC 3 NTs, BC 3 nanobuds and BC 3 NTs with different kinds of defects. In addition, we modeled the corresponding CNTs to validate the results and understand how the replacement of a quarter of the carbon atoms in the CNT by boron atoms affects the properties of the newly formed nanotube. The results showed that the variation of mechanical properties as a function of diameter and temperature was rather limited, regardless of chirality. The Young's modulus, failure stress and failure strain of the zigzag single-walled BC 3 NTs (SWBC 3 NTs) were lower than the armchair ones, and were lower than those of the corresponding CNTs too. Furthermore, adding a second and third wall to the SWBC 3 NTs significantly improved their mechanical properties. Finally, we modeled BC 3 nanobuds with 1 to 4 C 60 attached to the surface of SWBC 3 NTs and observed that the properties decreased as the number of fullerenes increased. Moreover, considering defective SWBC 3 NTs revealed that two-atom vacancies and Stone-Wales defects resulted in the highest and lowest reduction of mechanical properties, respectively.