Tires: TIRE SIZE, dodge durango, fuel mileage

Question
IVE GOT A DODGE WITH 265/70/17 TIRES ON IT AND IM BUYING A SET OF RIMS OFF A DODGE DURANGO WITH 245/70/17 TIRES ON IT WHAT WILL THIS DO TO THE FUEL MILEAGE OF THE TRUCK AND WHAT ELSE WILL IT AFFECT? THANKS

Answer
Wes,

You have gone down 2 sizes.  Assuming the P265/70R17's were the original tire size, you've increased your risk of tire failure back to the days before the Ford / Firestone thing.  You see, one of the lessons that came out was that using larger load capacity tires resulted in fewer tire failures.  I don't recommend this move.

You also probably will hurt fuel economy due to the smaller diameter tires.  This might be compensated for by your change in driving style, because the vehicle will accelerate quicker and you'll probably back this off a bit.

Plus the speedometer and odometer will be off about 4% reading faster than you are actually going.