thanks for the the info

Hi I am new to model trains and just perched a bunch of Bachmann fright cars and noticed that the trucks are looser on some cars than others.

How loose should the trucks be?

I know that they should be loose enough to rotate freely but some of them have a lot of play up and down and just seem like they are loose. Are they supost to be loose to allow the car to lean on the curves for better handling?
thanks