Assuming that the purchased air pump complies with the relevant manufacturing standards: the civil air pump is calibrated in this way before design. It is normal that the value is slightly higher than the actual value. This is for safety reasons. Different altitudes will be considered during research and development. , The margin of change of temperature difference in four seasons;
The so-called tire pressure value is measured under the premise of a specific temperature and standard atmospheric pressure. Therefore, not only the air pump, but also the tire pressure value you get at a certain moment "how much do you think it should be" may not be accurate;
3. It is necessary to know whether the tire pressure is reasonable for safety reasons. The easiest way is to understand the inflator and the actual error value through use, so that you can know it beforehand.