What gears should I choose??

First of all, I want to thank you DC for this write up and the info you have provided. Second, I have an 01 F250 with a 4.5inch lift and 315s (roughly a 35) and it has 4.10 gears in it. It is my DD and I get horrible gas mileage with it, roughly 13 on a good day. Highway isnt any better. At about 70mph, im a little over 2100rpms from what I can remember. I dont really do much pullin, except in the winter, but I want to be able to pull a heavy load when needed. Also, the truck is very heavy, roughly 8500 to 8700lbs. Do you think the gears are the cause of my horrible fuel mileage? If so, what gear would you suggest moving too? Thanks again

OK i got a question for you, in your standard sizes like a 285/75, the second number is the width right? now if that # is bigger is the tire wider or is it vice versa?

bladerunneroif said:

OK i got a question for you, in your standard sizes like a 285/75, the second number is the width right? now if that # is bigger is the tire wider or is it vice versa?

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The first number is the width. The second number is the aspect ratio. In your example, 285mm width x .75 aspect ratio = 213.75 mm. That dimension (213.75 mm) is the height of the tire from the wheel to the tread. The aspect ratio is used for determining what the overall diameter is of the tire. So take 213.75 + 213.75 + (16 x 25.4) = 833.9 mm (32.8") diameter tire.

Thanks

DCSpecial said:

Yes EGTs will drop.
I'd do 4.30s or 4.56s....most likely 4.30s since you have a SCT and some other go fast goodies.


On my 7.3 I ran 3.73s and 38s....then went to the 4.56s with 38s and my EGTs (cruising, WOT, etc..) dropped 200-300* across the board.

Now I'm running 40s and the 4.56s, EGTs are <125* more than they were with the 38s. But, I'll be dropping back down to 38s soon.

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what gear manufacturer are you using i was running a 488 from genuine gear with 46's on a srw 7.3 and i stripped the pinion 5 times now im running a drw with 38's and was gonna go with yukon 488 do you have any opinnion or useful advice...