Tires and MPG... - PowerStrokeNation : Ford Powerstroke Diesel Forum
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post #1 of 20 (permalink) Old 05-12-2008, 08:44 PM Thread Starter
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Tires and MPG...

Looking to get new tires and I was wondering what experiences were.
What is it that drops mileage, height or width? I'd think increased height would effectively help, and wider tires would add road resistance.

Stock tires at 235/85 are 7" wide.
265/75 are same height but 8" wide.
285/75 are about 1" taller and 9" wide.
I ran the 265/75 when I first got the truck and mileage was really good. I swapped them (they were dry rotted) to the 285's I already had and winter hit so I'm not sure on mileage with them.
The 285's fit the truck well, but I want to keep them for winter tires (steel wheels) and get a new set for the alum rims to run in the summer.

Is there that much of a difference in drag on the 285 vs 265? I've read the 265 is comparable to the 235/85 as far as mileage goes but they have 1" wider tread. ??
I'd like to get 255/85 but I have only found them in MT tread, and I don't want those, I want AT tread.
Thanks.
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post #2 of 20 (permalink) Old 05-12-2008, 09:00 PM
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Re: Tires and MPG...

im running 285-75-16's mudders on mine and I got just over 18mpg this weekend with my DP in 80 econo

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post #3 of 20 (permalink) Old 05-12-2008, 11:14 PM
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Re: Tires and MPG...

For running larger size tires I've seen mixed results. Some go higher MPG....some do the same MPG.....& some go lower.


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post #4 of 20 (permalink) Old 05-13-2008, 02:44 AM
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Re: Tires and MPG...

well a bigger tire should in theory reduce MPG because of the added weight (and it is rotational weight so it is on the worst spot...) Now when you go wider you are you adding weight but when you go taller that added weight has more effect because the lever to do the torque no is bigger (weight acting as torque opposing the engine) So not only do you get more weight but it now has a bigger multiplier because of the added diameter.

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post #5 of 20 (permalink) Old 05-13-2008, 03:30 AM
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Re: Tires and MPG...

I have found no difference in MPG using either 235s or 265s. But when you get to 285s the MPG begins to roll off.

Don't go smaller either. My MPG dropped off with 225-75s.

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post #6 of 20 (permalink) Old 05-13-2008, 12:12 PM Thread Starter
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Re: Tires and MPG...

I got my best mpg with this truck with 265/75 on alum rims.
Think the alum rims help mpg at all (weight savings)???
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post #7 of 20 (permalink) Old 05-13-2008, 01:20 PM
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Re: Tires and MPG...

From my own experience, my truck got 22mpg when it was new with 235/80. When I changed it over to 265/75 It then went to 19mpg. Once I changed it from 3.55 to 4.10 gears it went down to 15.5. Now I have 285/75 and Im at 14.5 or so.

If I was going to drive it all the time I would go with 235/80 (even though they look bad) and 3.55 gears. Would be nice to get back in the 22mpg range.

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post #8 of 20 (permalink) Old 05-13-2008, 04:08 PM
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Re: Tires and MPG...

Shaw: Did you recalibrate the speedo or are you just estimating the difference the tire size and gearing effects the odometer?

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post #9 of 20 (permalink) Old 05-13-2008, 05:11 PM
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Re: Tires and MPG...

Quote:
Originally Posted by mazdaparts View Post
Shaw: Did you recalibrate the speedo or are you just estimating the difference the tire size and gearing effects the odometer?
the 225 to 265, no because it was very close in height, the 265 to 285, yes. The gear change no because it doesn't need it.

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post #10 of 20 (permalink) Old 05-13-2008, 05:12 PM
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Re: Tires and MPG...

Edit my original post from 235/80R16 to 225/80R16

"It's JUSTa 7.3"

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