Previously, I have been using the minimum recommended tire pressure printed on the tire, on all the bikes in our household.
I recently tried the tire pressure calculator online:
The calculators recommend pressure that is much lower than recommended tire pressure from the manufacture. Even for me at 170 lbs, calculator is 20% lower than the tire manufacturer's minimum pressure. For the kid at 100 lbs, it is 40% lower. And that is for road. For gravel, the delta is even larger.
Is there any reason tire manufacturer use minimum pressure number that is higher than the calculator? For the manufacturer, is it better to error on the high side? Then as user, which should we follow?