Have a stock 2006 Dodge Laramie 2500 Diesel 4 x 4. I want to change my tire/wheel size.?

I have a stock 2006 Dodge Laramie 2500 Diesel 4 x 4. I want to change my tire/wheel size. The stock tire is 265/70/17 and I want to put a 305/55/20 on the vehicle. The new tire has about the same amount of rubber surrounding the wheel, but is obviously a much wider tire and 3%26quot; taller because I am going from 17%26quot; wheels to 20%26quot; wheels. I was told there should be no rub, but I am not 100% certain. I am also would like to know how much of a fuel hit I will take?Have a stock 2006 Dodge Laramie 2500 Diesel 4 x 4. I want to change my tire/wheel size.?there's a possibility that they will rub a little on it,you may have to use a leveling kit on it to stop that ,on the fuel you,ll probably loose at least one to two miles per gallon on it,my neighbor just changed his and it hit him pretty hard around 4 miles to the gallon in the city out on the road it doesn't do to bad,you wont know until you try it,each truck will run and perform differently ,and the mileage wont be the same on no two trucks either,good luck with it.Have a stock 2006 Dodge Laramie 2500 Diesel 4 x 4. I want to change my tire/wheel size.?We had to put a leveling kit on my friend dodge with 305's cause it did rubHave a stock 2006 Dodge Laramie 2500 Diesel 4 x 4. I want to change my tire/wheel size.?you will need a programmer to adjust your spedo and odometer as the larger tire will throw that off. also to compensate for the larger tires. you can go for a set of 4.10 gears and will help on the gas mileage some.