Wheel Specs?
 

Ok so I've been hunting on the internet all night trying to find the backspacing and offset and blah blah blah for my wheels cuz I'm thinking about buying new ones.. I cant just go measure cuz my wheels have tires on them and I cant yank one off.. So if somebody could please tell me the specifications so I know what the heck I need I would really appreciate it..

The truck is a 91 3/4 ton Dodge