Which way would you go?

[BigDs_2000]

F250 4x4 SC SB. 4.10 gears w/auto. Right now I have 285 tires on.

This is the two ways I could go.

Leave the 285 tires on and go to a higher gear, ie: 3.73 or 3,55.

Get another set of tires and rims at a cost of about $1200 and switch the taller tires for daily driving. (315 or 325s)

Put the 285's back on when I tow my 5th wheel camper.

I haven't checked on cost of replacing the gears yet.

All this has to do with better fuel mileage. Right now, just daily driving I'm around 13-14. That sucks.

How are each of these options going to affect my mileage? Which way is best for me? Slowing the motor down , and losing power I wouldn't think should be an issue, as I have stage 2 injectors, PHP tuner, 4" exhaust, wicked wheel, SB intake now. As long as my trans doesn't take a crap on me until I get a BTS trans installed.

I hope all this makes sense.

Let me know what you think. Thanks

[Zaairman]

Are you sure you have 4.10s? What rpm are you at at 70 MPH?

Switching gears is gonna run you somewhere around $1500-2000 for both axles.

[BigDs_2000]

The tag says 4.09 actually. I'm not sure about rpm at 70 but at 65 it's about 1900.

Just got a price on gears it was 1900+ tax. That buys a lot of fuel even at todays prices.

[captinbill2003]

14-15 mpg is not bad at all, thats what my old Dually with 4.10's got. Your only going to bump up to maybe 17-18 with a gear change. if you look at the cost benefit, it is costing you .27 cents a mile to drive your truck based on $4 a gallon to make it easy on math. A gear change will dop that to .22 cents. The difference is only .05 cents so that means that you would have to drive 40,000 miles before you have justified the cost of the gear change (based on a $2,000 install price) my reccomendation would be an intake, exhaust, and chip with the 4.10's that way you still have the gears for real heavy pulling and you spent your money increasing mileage and power instead of loosing low end brute force and gaining no power, it will cost about the same.

[GotDiesel85]

Originally Posted by captinbill2003

14-15 mpg is not bad at all, thats what my old Dually with 4.10's got. Your only going to bump up to maybe 17-18 with a gear change. if you look at the cost benefit, it is costing you .27 cents a mile to drive your truck based on $4 a gallon to make it easy on math. A gear change will dop that to .22 cents. The difference is only .05 cents so that means that you would have to drive 40,000 miles before you have justified the cost of the gear change (based on a $2,000 install price) my reccomendation would be an intake, exhaust, and chip with the 4.10's that way you still have the gears for real heavy pulling and you spent your money increasing mileage and power instead of loosing low end brute force and gaining no power, it will cost about the same.

Definately agree 100%, he can get that 17-18 withe the right intake and exhaust combo with the right chip, Might try a CFM+ plenum to. I dnt know how any feels about fuel additives but the grey bottle of dieselKleen seems to give me and extra mpg as well

[BigDs_2000]

Thanks for the answers. That's what I was looking for. I already have the chip, intake, exhaust, plus the stage 2 injectors. I guess I'll learn to live with it. Thanks again.

I don't want to put any more money in this truck if I don't have to. I got hosed enough trading my dually for this truck.

[Zaairman]

It sounds like you have 3.73 gears already. At 70 MPH (assuming your speedo isn't too far off), you should be right at 2000 RPM. Your 1900ish at 65 makes me think that you have 3.73s. With 4.10s, you'd be right at 2000 RPM at 63-64.

[coot1]

In my case, when I went from 265 tires to 305's my mileage dropped. Didn't matter whether I was towing or not.

[captinbill2003]

Originally Posted by coot1

In my case, when I went from 265 tires to 305's my mileage dropped. Didn't matter whether I was towing or not.

I doubt that your mileage dropped a noticable amount. You need to remember that the hand calculated fuel economy doesnt work if you dont take into acount the % your speedo is off. In my case, doing it by hand with 395/65R18 shows I get roughly 11 mpg, but my speedo is appox 19% off. So when I correct the odometer mileage Im actually getting appox 15 around town the way I normally drive. There are a few sites that offer a comparison calculator from stock to current size. You also can go to the Ford dealership and have them recalibrate it up to like 365 I think, or find a shop that runs Autoenginuity and that can go up to a 395.

[03_Turbo7.3]

how many miles do you get to a tank..?

and if you honestly wanted different gears, if you actually have 4.10 i paid 650$ for 2 complete diffs.. id buy new diffs and haul the gears out and sell thema gian before i paid 2Gs for a ring gear and a pinion