What tires with a 5 - 7 drop?

I have a 1998 extra cab GMC 3500 with a 454. I am saving up to lower it, but need now tires now. What size tires will i need with the 5 - 7 drop? Will the stock size fit? I will be towing a 5th wheel so i need to keep the ratings up and dont want to go to low profile if i dont have to.

225/70/16 will fit with some rolled fenders, however they will still rub sometimes in the front when turning into an incline.

I dont see e load range in a 225/70/16 ...... did you mean 225/75/16/

75 series will work also if you are wanting a tire with and e load rating. Rubbing will still occur just like on the 70s. 225/75/16s were a common stock tire size on most stock Chevy 3500s.