I am trying to understand the relationship between the Physical Resistance, character member - resist_physical_mod, (PR) and Armour Rating (AR).

Here's my question. Is physical resistance replacing armour rating or is physical resistance different than armour rating?

Since there is no longer an entry for AR in the status gump or the paper doll (I can't remember where it used to be displayed.) I am assuming PR replaces AR. If this is the case do we no longer use/need armour zones?

there is a setting in uoclient.cfg AOSResist 0/1

the status gump uses the values according to what you have that value in.

About AR and Physical Resistance

AR is using armozone.cfg to determine how much of the AR you have given some part gives the actual AR, while Physical Resistance doesnt use that config anymore, and you can give values to armors / piece.