We studied the effect of pilot balloon design on the ability of experienced anaesthetists to assess and inflate tracheal tube cuffs to safe pressures. A model trachea was designed, incorporating a degree of compliance and an air leak, to evaluate six different pilot balloons grafted onto identical tracheal tubes. Pilot balloons were inflated to one of four pressures and anaesthetists were asked to estimate whether the pressure was acceptable, too low or too high. Anaesthetists were then asked to inflate the cuff of each tube. Overall, 103 (42.9%) of anaesthetists’ assessments of tracheal tube cuff pressures were correct (33% correct would be expected by chance, p = 0.002). Pressures generated by anaesthetists inflating tracheal tube cuffs were very variable. Median (IQR [range]) pressures for each pilot balloon ranged from 29 (17–43 [9–56]) cmH2O to 74 (49–114 [4–140]) cmH2O (p < 0.001). The design of the pilot balloon significantly affects anaesthetists’ ability to inflate tracheal tube cuffs to safe pressures.