I dont have any way to measure it exactly so this all just comes from personal observation. When i had the stock tires and wheels on my truck, I'd get around 260 miles on about a half tank. Had new, bigger, tires and wheels put on a few months ago. Now I get about 160 miles on a half tank. I know going bigger would effect gas mileage. Knew that going in. The Stock tires/wheels were 255/65/17's . New ones are 285/60/18 with 18x9 rims.

Is it me or is that a bit extreme? Around 100 miles less per half tank? Is that right or should i be concerned there may be something else wrong?

Thanks

 

still winter blend of gas. give it a few months before you actually calculate it. also did you correct your speedometer? if not its off and causing you to think your getting worse MPG than you actually are

 

I have not had speedo corrected, but i do know i'm going something like 2.8 MPH faster then what the speedometer says.

 

That means that you're actually going further than the 150 miles your odometer says you're going. I think the Ford dealers can correct the speedometer, which will in turn correct the odometer. Or you can use the Edge (maybe other tuners too) to make this fix yourself.

 

Doesnt seem like it would be that big a drop off imo though. Ohwell, Truck is due for its first oil change any day. I'll see if i can get them to fix the speedometer.

Thanks for the info.

 

Keep in mind that the ford speedo is around 2 mph off from the factory built in , so if you got your number from a gps then you could be close to 4.8 mph off.

 

how many k u guys gettin to a tank with the 5.4???

 

About 300 before the low fuel indicator comes on. Its always thirsty.

 

no idea yet. I try to not let the 35.7 tank get to empty!

 

I never let the tank get below 1/4 left, at that point i usually have around 400 miles on. But I also have the 35.7 gal tank.

When I am running my summer setup, Nitto 325/60/18 on 18X9 wheels, I usually see around 1-1.5 mpg drop from my stock wheels/tires (FX4 wheels, 275/65/18 Goodyear AT/S) that I run in the winter. That is with my speedo being corrected with my Edge.

 

Im at around 220 miles at 1/4. 30 gal. tank.

 

i get around 330 miles to a tank in the city with the 30 gallon tank with my 35's. my speedometer is w/ in 1/2 mph to my GPS as all times

 

Came up with the speed difference from an online calculator. Dont know how accurate it is but thats what it said.

Forgot to mention earlier, I have a 25 gallon tank.

 

I love these threads.

"I raised my truck by putting big honkin' big tread tires on the thing. Now my MPG stinks. What am I doing wrong?"

 

. I knew it would go down, just not that much. Tires arent THAT much bigger.