Jared26

I have a 2011 FX2 5.0, I recently replaced the stock wheels with 275/70/18 BFGoodrich All-terrains. Im not an idiot I expected there to be a change in my gas mileage from going with a slightly larger tire. But I was very surprised to see it go from around 15-16 city 18-19highway to 12 city and about 13.5 highway.

Is this normal?

I have read stuff about changing the gear ratio to make it fit to the larger tires, but I dont know where to start? Any help or advise would be appriciated.

feifel

iTrader: (3)

I was hit hard with mine too I have the same tires with an ecoboost the best I can get is 15.2

ruff rider

I just put on 275/65/20 stock was 275/55/20 and I dropped mpg's also. Two things to remember
1. I am now running winter gas here in Utah. My 2009 F150 would drop about 1-2 mpg in the winter and was 100% stock.
2. With the tire being larger in rolling circumference when I go 100 miles on the odometer I have actually gone 111 miles. I have to factor that in when I figure out what I get in mpg.

So after doing the math with my new tires I have lost a little over 1.4 mpg over what the truck did with stock tires. I can live with that.

21RRF150

iTrader: (1)

You've had the truck recalibrated for the new size tires right?

harrison14allen

I had a big loss as well. I had 2 other F150s and a Z71 that I ran 285s on and the most I ever lost was 1.5 mpg. I dropped 3.5 mpg on my 2011 eco after upgrading my tires

Jared26

No I have not recalibrated anything, you talking about the speedometer and gears?

21RRF150

iTrader: (1)

Any time you put on bigger tires the speedo needs to be recalibrated. It can be done by the dealer or a tuner. I don't know much about it, but have read countless threads on the topic. And it takes care of the mpg issue. Maybe someone else will chime in with better info, or if you go over to the 09+ forum, there's tons of info over there.

sdmartin65

I went to a slightly larger tire and its also an all terrain vs the stockers that are barely all season. My mpg got hammered. I think its a combination of these two new factors. I also lose a bit when its gets colder.

Jared26

Anyone have an idea how much a dealership would charge to recalibrated the speedometer?

Jared26

Over the weekend I disconnected my battery and let it sit for 20 mins then reconnected it to reset the computer and try to fix a different issue I was having. To my surprise it seemed to also correct the lower MPG readings that I was getting. It's now telling me that I am getting about 14 in the city, up from 12 before. That will make me sleep a little better at night, I can deal with that.

Thanks for the help and suggestions!