Ecoboost Larger Tire Programming
06-28-2011, 03:12 AM
#11
3.73 vs 3.55 is about 5% difference.
31's vs 33's is about 6% difference.
I would think telling the computer you have 3.55's instead of 3.73's when you changed from 31's to 33's would be pretty close to accurate.
BTW, dln11, could you post a picture of your front suspension to show the UCA and axle angles? Also, was the AS piece actually 2 inches or did it raise the truck 2 inches?
31's vs 33's is about 6% difference.
I would think telling the computer you have 3.55's instead of 3.73's when you changed from 31's to 33's would be pretty close to accurate.
BTW, dln11, could you post a picture of your front suspension to show the UCA and axle angles? Also, was the AS piece actually 2 inches or did it raise the truck 2 inches?
Last edited by sk8inrj1; 06-28-2011 at 03:15 AM.
07-29-2011, 11:40 PM
#13
Current Mileage
DLN11,
That lift and size looks really good. Assuming you haven't done any mods to the rear axle ratio or computer, would you post some current MPG stats (with conditions)?
I'd like to know what that larger tire size alone does to the Eco's MPG.
Thanks in advance.
That lift and size looks really good. Assuming you haven't done any mods to the rear axle ratio or computer, would you post some current MPG stats (with conditions)?
I'd like to know what that larger tire size alone does to the Eco's MPG.
Thanks in advance.
Last edited by RAINCO; 07-31-2011 at 11:32 AM.
07-30-2011, 12:28 AM
#14
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305/55/20
I just put some 305/55/20s on my ecoboost and took a 1-1.5 mpg hit. was averaging high 16s (mpg) and now am in the low 15s.
My truck only has 1300 miles so in another couple tanks if i remember Ill post back.
My truck only has 1300 miles so in another couple tanks if i remember Ill post back.
07-30-2011, 01:19 AM
#15
b) your truck's computer is reading your miles traveled / gallons used based on the stock size. since u have bigger tires now - you are actually traveling more miles / revolution than the computer thinks. so this will show even lower avg. mpg
the only way to know is to program the right size in and do the mpg calculation yourself.
or just dont look at that damn avg. mpg reader and just enjoy your badass truck!!!!!
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IMTALLERTHANU (11-18-2013)
07-30-2011, 01:22 AM
#16
a) you will lose a little mpg with taller, wider, heavier wheels/tires
b) your truck's computer is reading your miles traveled / gallons used based on the stock size. since u have bigger tires now - you are actually traveling more miles / revolution than the computer thinks. so this will show even lower avg. mpg
the only way to know is to program the right size in and do the mpg calculation yourself.
or just dont look at that damn avg. mpg reader and just enjoy your badass truck!!!!!
b) your truck's computer is reading your miles traveled / gallons used based on the stock size. since u have bigger tires now - you are actually traveling more miles / revolution than the computer thinks. so this will show even lower avg. mpg
the only way to know is to program the right size in and do the mpg calculation yourself.
or just dont look at that damn avg. mpg reader and just enjoy your badass truck!!!!!
07-30-2011, 05:09 AM
#17
what hes saying is....lets say you went from a stock 31 inch diameter tire and you were getting 18 mpg on the computer, using the formula for circumference "C=(pie)x(diameter)" then the circumfernce of a stock wheel is C=3.14x31 which equals 97.34 inches which translates to 8.11 feet. so in the trucks mind for every rotation of the axel it has traveled 8.11 feet. in actual reality you traveled 3.14x35= 9.16 feet with that one rotation. There are 5,280 feet in a mile. So in your trucks computer stock its saying with 5,280/8.11 feet=651 rotations of the axel per mile, and you can go 18x651=11,718 rotations per gallon. now lets say you lifted it and put 35's, earlier we figured out that your going 9.16 feet per rotation. the computer is reading 16 mpg now since you changed tires...so that comes out to 16x651= 10,416 rotations per gallon. sucks we have less axel rotations per gallon now! but wait, we are traveling farther per rotation, so lets figure out what 10,416 rotations x9.16 feet = 95,410 feet traveled which comes out to be in all actuality 18.07 mpg! (95,410/5,280)=18.07. Now if you think well I dont use the computer I calculate manually, then just remember your odometer is still gonna show how far you traveled by counting one rotation as 8.11 feet and not 9.16. so thats off too. good news is...when your truck hits 100,000 miles....its actually got 113,000 miles on it! talk about extended warranty! sorry if this post is boring and or hard to read.
07-31-2011, 11:03 AM
#19
MPG stats for 3.5v6eco,3.55axle,larger tires
Typo in last post, meant to say "lift" not life".
In resp to TopGun's post:
This brings up a good point. A larger tire with a higher circumference will give you more "road travel" per revolution, to his point. This is true at any speed and in any condition. Even if you don't follow TG's specific example, think of 2 tires (one is taller in height than the other) sitting beside one another. If you roll them both once, the taller tire will cover more distance.
The second and equally significant variable is the amount of stress put on the motor to achieve that revolution. Though you get more travel, taller tires are harder to spin at any speed and in any condition. In the case of a load-bearing tow, this variable can have a profoundly more significant effect on overall MPG than tire circumference.
I got a 3.5 V6 yesterday and it has a 3.55 rear axle ratio. I pondered forever on the axle ratio, but ultimately made a decision based on my particular use. This combination is at it's best on the hwy and/or w/o a tow load. I don't mind slightly sluggish performance for the rare tow/haul I do each year. I much prefer better MPG during the 95% of the time I use it w/ nothing behind or in it.
Tire selection is the only thing that's got me concerned. I don't put big stuff on - just something to fill up the wheel well a little. I put some Goodyear Silent Armor on an 06 FX4 before and they was perfect (but it had a 3.73 rear axle). Awesome tires, those SAs.
This new truck has P275/55/20R stock tires. I'm considering Goodyear SA P275/60R20 or LT285/60R20, probably the latter.
If I put taller tires on, this 4x4 could rival 4x2 (w/stock tires) hwy mpg on the highway, once I got up to those speeds. I'm just skiddish that too tall a tire would create so much more stress on the motor at the low end (take-off, city driving, stop and go) with this axle ratio that it'd be an overall net loss. I can handle 1-2 MPG loss on the low-end, but anymore more than that would be a net negative.
Does anyone have any experience with a 3.5 V6 and 3.55 axle with slightly larger tires than stock, specifically around town/non-hwy?
In resp to TopGun's post:
This brings up a good point. A larger tire with a higher circumference will give you more "road travel" per revolution, to his point. This is true at any speed and in any condition. Even if you don't follow TG's specific example, think of 2 tires (one is taller in height than the other) sitting beside one another. If you roll them both once, the taller tire will cover more distance.
The second and equally significant variable is the amount of stress put on the motor to achieve that revolution. Though you get more travel, taller tires are harder to spin at any speed and in any condition. In the case of a load-bearing tow, this variable can have a profoundly more significant effect on overall MPG than tire circumference.
I got a 3.5 V6 yesterday and it has a 3.55 rear axle ratio. I pondered forever on the axle ratio, but ultimately made a decision based on my particular use. This combination is at it's best on the hwy and/or w/o a tow load. I don't mind slightly sluggish performance for the rare tow/haul I do each year. I much prefer better MPG during the 95% of the time I use it w/ nothing behind or in it.
Tire selection is the only thing that's got me concerned. I don't put big stuff on - just something to fill up the wheel well a little. I put some Goodyear Silent Armor on an 06 FX4 before and they was perfect (but it had a 3.73 rear axle). Awesome tires, those SAs.
This new truck has P275/55/20R stock tires. I'm considering Goodyear SA P275/60R20 or LT285/60R20, probably the latter.
If I put taller tires on, this 4x4 could rival 4x2 (w/stock tires) hwy mpg on the highway, once I got up to those speeds. I'm just skiddish that too tall a tire would create so much more stress on the motor at the low end (take-off, city driving, stop and go) with this axle ratio that it'd be an overall net loss. I can handle 1-2 MPG loss on the low-end, but anymore more than that would be a net negative.
Does anyone have any experience with a 3.5 V6 and 3.55 axle with slightly larger tires than stock, specifically around town/non-hwy?
Last edited by RAINCO; 07-31-2011 at 11:33 AM.
07-31-2011, 12:02 PM
#20
RAINCO,
I don't think you would ever be able to keep up with a 2wd fuel mileage just for the fact that your 4x4 is so much heavier with the added front drive, transfer box and heavier suspension.
For those that haven't bought your new truck yet or thinking about trading for a newer model and you are going to mount the larger out of factory specified tires you would be a lot better off if you opted for a 3.73:1 or may even a 4.10:1 rear-end ratio.
I don't think you would ever be able to keep up with a 2wd fuel mileage just for the fact that your 4x4 is so much heavier with the added front drive, transfer box and heavier suspension.
For those that haven't bought your new truck yet or thinking about trading for a newer model and you are going to mount the larger out of factory specified tires you would be a lot better off if you opted for a 3.73:1 or may even a 4.10:1 rear-end ratio.
Last edited by shortride; 07-31-2011 at 12:11 PM.