Right now im getting about 17-18 mpg with 75% highway driving. I decided on getting the 31" goodyear duratracs after i do my 2" BL. From the reviews, I heard they perform on road like an A/T tire, we will see about that.

so im just curious on how far down my mileage should go after that. Im hoping that because i have the 3.73 gearing it wont change a whole lot. but i know with the 2" BL you are stretching the truck out which means more wind resistance.

 

I would expect a 1-2 MPG decrease at least. I put 31" tires on my 2000 Blazer that I just sold and had Pro Comp Steel rims. My MPG went from 17-18 to 14-15 on the highway. Depending on how I drove I could get slightly better at times. Mine also had 3.73's.

My current blazer has the stock 235/70/15 Uniroyals on it now and a 3.42 rear. The previous owner had just put these on otherwise I would be picking up some 30" A/T's for sure (got tired of the 31"s rubbing). I am averaging just over 18 MPG at this time but some better, bigger tires will be going on before next winter.

 

My buddy gets 15-17 depending on his driving. He has a 96 crank/shackles and 2inch bl on 31s.


Makes me enjoy my "little" 180 hp 3.4 with the same mods even better as I get 18-20mpg (3 bl instead of 2)

 

I'm in your same boat. My 2 inch body lift will hopefully be installed this weekend and I'm getting 31's A/T, but I think I may have the 3.42 ratio instead of the 3.73. But I'm hoping for the best, hopefully my mileage won't go down the pooper.

 

ehh 1-2 isnt horrible i just filled up and i got 18 with about 60% highway.

ill do some scary math with those numbers tho:
So if i get an average of 18mpg over the last 50,000 miles thats roughly 2,778 gallons of gas which at current gas prices is $9,305 ($3.35 x 2778= $9,306)

Assuming i get 50,000 miles out of these tires, with that 1-2 mpg drop, we will call it 1.5, the extra money i will spend works out to be: (50,000/16.5= 3,030gallons), (3,030 x $3.35= $10,150), ($10,150 - $9,306= $844 <--- ouch!)

Im going to college so i really dont drive a lot, so spread that $844 out over about 7 years and i guess thats not horrible. (but man i never thought about how much money goes into gas, in 50,000 miles i pay for my truck twice!)

 

Most mods to increase off road ability will lower fuel mileage. I would not sweat it, you can always an adjust your driving habit to help out. Good luck with the body lift and don't forget pics.

 

Think that's scary? I bought my truck in March and basically lost a month of driving it with the 2 trans rebuilds this year.

My buddy has a first gen xB that hasn't seen any shop time.

We both kept track of gas mileage this year. He gets nearly twice my mileage, has had his car MORE time than I have this year, put on more miles, and still has put in less than half the gas I have.