I have LR E tires on my GM 1500, I've never had enought load in the bed to need 80 lbs on the rear tires! needed 45-50. Or what an XL/ LR C tire is PSI rated too. Unless like mine you are running 8000 lbs per axle. WHY have LR E tires?
WIth this said, I have no idea what size you can do stock on a Dodge. I's swag I had clearance for the 28-65-18 32.5" tires I upgraded to vs 265-65's at 31.5". I did do a 2" strut leveling kit in the front, and a helper spring that lifted the rear around 1.5". My sone thinks his 305-65-18's will fit. He has a 4" lift on his 05 GM reg cab.
I've done 1" diam changes on my SW 3500's in the past with out issues.
Marty