I know the 2500's with 315's will rub at hard lock(the control arms),not bad at all.I ran them for 4 years without any issues.305's should not rub at all.
Also the lift will not help you,its all about the backspacing of the wheels.
here they are on a stk.2500(315's)...hope this helps you
they still hit the control arms at full lock with a 6" lift with stk. wheels and 315's