Just scroll down to page #47 in the following reference and read all about it.
https://www.ustires.org/sites/defaul...TruckTires.pdf
Your trailer's owner's manual will have the basic information. The generic Keystone one referenced below has the info on page #23.
https://www.keystonerv.com/media/914...anual-2019.pdf
Here is some info about CAT scales.
https://catscale.com/how-to-weigh/