HUGE DELEMA need advice ASAP

[jstarr]

i have an 05 6.0L F250 with a 4 inch exhast turbo back, aftermarket intake, SCT livewire 9600 programmer, 8 inch lift, and im running 40's. i am looking to re-gear the truck. the guy at the 4x4 store said he wouldnt re-gear the truck. im currently getting 9 mpg. i know if i re-gear the truck with 4;56 it would go pretty close back to stock as i could get. this is my daily driver. i know getting 15mpg is unrealistic. what gears should i run to help improve my MPG atleast back to 12 or 13. should i leave stock 3;73 or go 4;11 or 4;56..... please someone help. i would like to order gears in 2 days.

[BubbaJ]

What's your usage of the truck? City driving, highway? Mud running? Drag racing???


If you run 4.56's compared to 4.11's your going to have a weaker gear, but if your not going to be doing a lot of boosted launches, or in the mud going from no traction to lots of traction and such, you'll be fine with 4.56's, if you are going to be doing that, I'd go 4.11's....

But 4.56's will get your closer to stock, but the lower gear you go, the more top end you loose... With 4.56's and 40's I'd say 95 will be your fastest you can go...


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[jstarr]

i do mostly city driving.. not to far on the highway. no towing no drag racing. very little mudding.

[jstarr]

also i dont plan on going 95 mph.. not in that truck!! lmao

[skanj0]

With that size and weight of tire you really need 4.56s or even 5.13s. Your transmission will thank you, and your fuel mileage will recover a bit.

[BubbaJ]

I would definitely do 4.56's, if your ballsy you can run 4.88's which you will love for your city driving, but that's gonna make your highway rpm's kinda high at 70-75... Idk what you normally cruise at... But I would definitely not go up to a 5.13.... It's just to weak of a gear.. Eventually something will give.


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[Karls03]

Judging by the rate of change, to get the speedo to read right, you'll need a 4.73 gear. 40/31.5=1.26, then 1.26x3.73=4.73. So, if you are on road more, go 4.56, off road more, 4.88, 4.73 falls dead center between them.