Ok I run 35" and 3.55 gears. I only have a 4.6 and there is definitly some power loss. I am currently get 9.6mpg . Its pretty bad, I know there has got to be something wrong (as in I need to clean some stuff out) but it was an instant drop to 9 when I put the tires/lift on which I knew it was going to be bad but really? At first I thought it was just my speedo off but then when I got it corrected it was still 9. I need to do something to get it going a little faster (gryphon, gears). Being 17, I don't have money for both but I'm thinking gears would be the right choice? If I switch to 4.56 is that going to help with the mpg's? I drive like a grandma everywhere to try to help it and I mostly only drive it for a 10min drive to school going in and out of 2 towns and back during the week. Oh ya and I barely go over 60. So would 4.56's be my best bet?

 

There is nothing you can do to get your gas mileage back once you lift and put big heavy tires on - if you wanna play you gotta pay. All you are going to get back with gears is power. The money you spend on gears and/or a programmer will buy a lot of gas.

 

I thought it was suppost to help......? If your running at a lower rpm should that equal better mpg?

 

i get 15mpg in the summer and 12.5 in the winter running 3.55's and 35's with my superchips.

but yes, 4.56 would help you, but if you ever want to go bigger you might want to get some 4.88's, but you would still have to buy a programmer to correct your speedo.

 

depends on what you drive mostly. lots of highway miles will benefit from 3.55 gears but short trips will help with higher numerically gears (4.56). so yes they will help your mpg (1-2 mpg better at most if stop and go trips) but as glc said, it will not help alot as thats what we pay for when going bigger.

 

I am pretty new to the ford game but speaking form my chevy back ground 4.56 might be a little much if you ever plan to go anywhere other than the super market. i would lean more to 4.10s. And for ever going bigger than 35's. If you make that choice it will become a mud truck. Half ton trucks biger than 35's are hell to drive everyday. But 4.10s will help in the city and still give you some highway usage.Then later down the line you can add the programer and have a pretty mean truck.

 

Keep in mind you want your RPM's to be as close during your driving as they are with the factory tires. If you are doing say 2200 RPM's at 65 mph on the freeway on flat ground with stock tires, you want to get back to that with 35's. Also, there is an ideal power band that usually ranges between about 500 RPM or so. If you consistently run above or below that RPM range, you are not in your ideal power curve. I have built both Ford and Chevy and I've found for most rigs with 35" tires the 4.56's are usually the way to go. However, there are always exceptions. I had a 76 Blazer with a D60 and Corp14ff w/ 35's and I started with 4.56 gears. I swapped in a 700r4 tranny and I found I was running way low on RPM's. This really killed me in the mountains so I went with 5.38's and my power came back. I was staying in my ideal power band with those gears.

 

4.10's are fine with a 5.4 but the 4.6 is comparatively lacking in low end torque - so 4.56's would be better.

 

Ya I kinda thought that, so with it being a 4.6 and me making a lot of short trips it would be a good idea to go with the 4.56's...?

 

yessir...

 

Ok so what are the chances that my gas milage will go up or down? Because I'm thinking about the doing the gears even if it doesn't help my mpg but if it is going to make it get even worse then that could be a problem.

Maybe some people with the 4.56's might chime in with their avg mpgs.

 

I would like to hear as well, i just picked up my gears yesterday. Im hoping that with the gears my mileage stays the same but i am more or less regearing because i tow a boat most of the summer and its pretty tough on the truck. Wish i could help ya out but im not installing mine for a few weeks, wicked truck by the way gotta love the rancho lifts!!

 

If you can get your RPM's back to as close as stock as possible, you should be close to your original MPG. However, when you add larger tires you add weight and rolling resistance too so it won't be identical. I think I lost a couple miles per gallon when I went to 35's on other vehicles I have owned after getting the gears to match the tires.

 

Ya I just want to make sure my mpg is goin to go any lower....not really going to be the best as soon as gas hits $5