255/65/17. I'ma go up to a 265/70/17..

Is that a big difference as far as gas mileage is concerned, and would you say, get it reprogrammed? Thanks guys

 

That is a difference of over 1.5" in diameter. Also over 3mph difference at 65 (really going 68.36 instead of 65). Might be worth getting it reprogrammed for the larger tire.

 

Necessary to reprogrammed? If so, how much?

 

i had the exact same problem. went from stock highway tires to BFG's truck rides fine didnt really see a difference in HP and Torque. MPG got worst but i needed some AT's for the ranch.

No rubbing either, im glad i went with them. I also have A V6 so you should be fine

 

Did it get a lot worse, a lot of what I can find says like .5mpg.

 

Not a Big difference i can get around 17Mpg pulling a trailer with fourwheelers on the highway and around 13 MPG around the city

 

Hmm, Thanks

 

I made the size change that you are thinking about, and the speedometer went from reading 2-3mph higher than my actual speed to 1 mph or less lower. I can live with that.

The mileage I'm getting hasn't changed much since the change. 17-19mpg.
You just have to allow for the bigger tires and add 5% to the miles total when you calculate.

 

Yeah, my dad pays for my gas. So if I go bigger, and my gas mileage gets worse he's probably going to get pissed. I'm hoping it'll be small enough of a margain to where, I can just drive easier and make up the difference.

 

I went from the stock 255/70-17's to 275/70-17's, and my speedometer is bang on. I verified that on two different GPS units.
No noticeable difference in mileage.
Now I'm looking at eventually going with a bigger tire.

 

That's impressive. Screw all this, I need to find where has my tires!

 

Just on the speedometer difference, without correction, it will show a drop of 5% in mileage. This is not a true drop, just what it looks like due to getting less miles on the speedometer. You will get a real drop due to tire weight and rolling resistance. How much, can not really be calculated.
In another area, the change will affect transmission shifts.

 

Oh okay, so if I do that, How much would it cost to get it reprogrammed. Should I deal with it, until I get a tuner. Advice is greatly appreciated!

 

The dealer can program that size tire. Cost would be about 50 to 80. My dealer did this for me for nothing. YMMV.
A tuner can also do this and will cost 300+.