[zjrog]

As an offroader... I understand the desire for bigger tires. But, you don't always need to take a MPG hit just because of the larger tire.

I wonder what your current tire width is, compared to how wide the 32s are. You MIGHT get a small improvement from the taller tire, but if it is much wider you won't get any effect. As for speedo changes. You might watch and keep your speedo just under what the speed limit is, because the taller tire will have you going faster than the shorter tires. Will you get any benefit? Hard to tell, I don't know how you drive now. Watch your tire pressures. You might also notice a slight hit to performace too, since you will be making the effective gear ratio taller (good for highway,not so good for offroading)

I went from a 30" tire to a 31" tire on my Jeep. I also kept working with tire pressures to find something that worked for mileage but didn't make for a buckboard ride. I'd have to go check my notepad, but I think I settled at 36 rear and 33 front. BUT, I am noticing wear down the middle of the tires. I'm at about 3" over stock, and on 31" tires and can go almost everywhere I need to go. So my Grand Cherokee does fine. If I need more height or bigger tires, I'll go with my 90 Ranger and its 4 cylinder. Its on 31s but at 6" of lift, 33s will "look" better... And, on the 31s it was getting 28MPG consistently.

As mentioned here a bazillion times, the single biggest increase in mileage is adjusting the nut behind the wheel.