Hey guys, i've been going back and forth now between getting gears, and once i have enough money to blow on some gears im going to do so. Anyways i was just wondering what gear ratio i should choose, my choices are the 4.56 and 4.88. I myself have been considering 4.56 as i do some highway driving, but just as much city driving.

Some Specs:
Current GR: 3.73

2001 F250 7.3 Turbo Diesel: 4x4
Poweraid Throttle Body Spacer
AFE Cold Air Intake Stage 2
Superchips Cortex Programmer
MagnaFlow 5" to 6" Tip
8.5" ProComp Suspension lift on 38" Toyo Open CTRY MT




Thanks for any help guys!

are you looking for more fuel milage, more bottom end or what.

and what size tires are in your future?
do you tow?

4.30's.

Unless you are planning to add a couple hundred extra hp...in which case the stock gears will be fine.

yikes!!!!

Tranny's don't like your way of thinking...

4.11s and 38s are just a hair faster then 3.73s with 33s All else being the same

4.30s with 38s are the same speed as 3.73s with 33s. All else being the same

4.56s with 38s are the same hair slower then 3.73s with 33s as above. All else being the same

4.88s with 38s are the same hair slower then 3.73s with 33s as above. All else being the same

For example.

33" tires, 3.73 gears, 2k rpms = 74 mph

38" tires, 4.11 gears, 2k rpms = 77 mph

38" tires, 4.30 gears, 2k rpms = 74 mph

38" tires, 4.56 gears, 2k rpms = 69 mph

38" tires, 4.88 gears, 2k rpms = 65 mph

the throttle body spacer just might limit his power enough to save the trans...






(and did he say auto or manual?)

4.30's unless it's a city truck.

This chart you have is great...but the biggest thing that everyone forgets,...

Rolling mass/weight of larger tires....my suggestion...anything larger than a 38" tire,..add one gear ratio larger to offset the difference of the added tire weight from stock....

But then again...it all comes down to preference, and whether the person lives in a hilly area, flatland, mostly hwy, mostly city, or tows...

or how much power is on tap