ok ive seen a couple threads about gear ratio and whatnot and ive seen the "howstuffworks" link but it does not explain to me what i would want for my truck by my understanding lower is less powerful but more mpg? is there any truth to this or how does this work? lets see if we can get this explained without the "howstuffworks" link thanks in advance

 

Ill try and explain this as best i know, the lower the number say 3.31 or 3.55 which alot of f150s have is a highway gear. The ration between the pinion gear and ring gear is low and the tires will spin very fast and have top speed, but not alot of torque. Higher gears such as 4.10's or 4.30's are a good gear to upgrade to for oversized tires, and much better for towing. They give you power and torque down low where it counts, and is much more practical for daily driving. As far as MPG goes it all depends on if you drive city or highway and what size gear and tire you have i have a link that will help you out.

http://www.4lo.com/calc/geartable.htm

 

so basically 3.31 is the lower of the highway gears so basically less low end power more mpgs and 3.55 is highway but a little more low end

 

The higher your gear ratio (lower number) means less torque and lower RPMs at higher speeds. Think about it as the tires are the first number, 1 and the drive shaft is the second number, 3.55 or whatever. That means the driveshaft has to spin 3.55 times in order for the tires to spin once. As you know a smaller gear turning a bigger gear increases power and decreases speed so the more drive shaft rotations to tire rotations means more power and less speed. That is what as the ratio goes up, the greater power you have at the wheels and the lower the top speed is at the same RPM.

 

if u get a chance, get the July issue of petersons 4 wheel and off road. it breaks down the science of proper gear ratios, axles, lockers, ect. its VERY informative. i learned alot just from reading it. just a thought.