[Wavery]

The pressure in the tire determines the amount of flex that the sidewalls will have. The tire air pressure is part of the structural integrity of the tire......lower the pressure.....lower the structural integrity of the tire.

It's true that you "Can" adjust the tire pressure lower for lighter loads and this may smooth the ride slightly without exceeding the load limit of the tire. However, it does cause more flexing in the sidewalls which shortens tire life. Only you can determine if it is worth it.