i have a 2002 with the 5.4L and the 3.55 gears. im going from the stock tires which are 31.5 to new tires which will be 34.5, any suggestions on what gears would work best, i dont mind losing alittle gas for more power.

 

i would recomend 4.56, you will lose some mpg on the highway but you will gain in city driving you will probably be running about 150 to 200 rpm higher than you are now at 75 mph, hope this helps

 

if thats true, that seems pretty good. i found this on a web site;

new tire size
---------------- X old gear ratio = new gears
old tire size

with that, why new gears should be 3.89. that seems why to low to make any power. did anybody else upgrade to 35's, what gears did you use?

 

when i had 35 i had 4.56, that is how i know the rpm, you will love 4.56 with 35" i did

 

if it makes more power and is only 200 rpm's above what stock would be that sounds pretty good

 

4.56 is the gear you want as long as you don't mind a mile or two lower milleage on the highway. You shouldn't notice much difference in the city or the trail though.

3.73 would bring you the closest to stock power/milleage.

4.10 would be only slightly noticable on the lower-end of the rpm range and not at all noticable on the upper.

I have never met anyone who said that they went with too much gear. Always take what seems like the best option and go one higher.

Check out this website to see the exact RPM difference between tire sizes at different gear ratios: http://www.florida4x4.com/tech/gearcalc.php (enter .76 for the 1st gear ratio and 1 for the t-case ratio, I think those are typical "overdrive" and "high range" on Ford drivetrains).

 

I've got 4.10s on street tires and love it. You'll want 4.56 for sure with 35s.

 

thanks for all the help, 4.56's is in then

 

golad to help and good luck