right now I'm getting right at 17 mpg with stock 265 BFG , if I was to go with say a 315 or 305 would my mpg suffer , and what I'd really like to run would be 35x12.5 -17 , any advice from someone who is actually using tires I'm thinking of trying would be Great ,

THANKS

 

post info about your truck.

 

truck is 2006/ Quad 4x4 /3:73 / 48RE

 

Mine is the same (06/4x4/quad/3:73/48re) and I'm getting about 17MPG with mixed easy 50/50 driving, the difference is that with the 305's the speedo is bang on (GPS verified) where I was out by about 6% with the stock 265's,...it's hard to calculate your MPG when the speedo is out so much IMO.

 

I gained mpg due to lower revs per mile with the 315's. Rpm is under 2000 at 70-75 mph

 

I went from 265s to 325/70/R18s and maintained a solid 17-18 MPG...depending on how I drive...

 

I know mine's a 2nd Gen, but wow. I lost when I went from 265's to 285's, and then lost even more going from 285's to 305's. I don't even want to list my mileage.

 

Me too big soft tires eat fuel. Down from best of 24 to 16 average.

 

It all depends on were you drive highway yes big tires will help by lowering RPMs!Town dont think so Just my two cents.

 

I don't ever check my in town mpg; only check it on trips, so I don't know what going to 315s did for me in town. On the highway, I never got more than 18.5 unloaded with the 265s, and right after I put the 315s on, I made an 800 mile trip and got 20.1 mpg. That was driving primarily 70mph.

 

I picked up about 1 1/2 mpg on highway trips going from 235/80 -17 dually tires to 35x12.50-17. The 4 inch difference dropped the revs nicely at 70mph.

 

Better mileage is obtained with taller, skinnier, higher pressure tires on the highway - not so much in the city, where the greater weight of the larger rolling stock carries an energy penalty due to increased resistance to acceleration.

My 37" Toyo MTs can get close to 20mpg on the interstate, but in-town mileage drops to ~15mpg.

 

That's what I did. Went from the stock 265's to 315's. Love the way it looks but with the auto your mileage will suffer. Cost me 2-3 mpg. Yes....I know my speedo is off, by 5mph. I checked it. Pulling there is a lost of power too. Due to the higher ratio created by the 315's. Guys out there with manual trans probably wouldn't experience any of this.

Mine are heavy lug MT's so it may not be as noticeable with an AT.

 

im hoping i get better mileage going from 33's to 35's on the highway. right now my rpms sit at 2200 @ 70mph

 

When did BFG's become stock on these CTD's? I've only ever seen Michellins on them.