how do i find out what ratio i have ? is there a door code because i didn't see one for axle ratio? maybe a tag on the pumpkin figured i'd ask before i get the 37's

 

there are two tags on you rear axel housing i did not see what you are driving but late modle f150's most came with 3.55 so your tag should read 3.55LS the ls is for limted slip if you truck was equiped.

hope this helps ya

Dale

 

The "Vehicle Certification Label" is on the drivers side door jam.

Rear axle ratio codes:
18 - 3.08
19 - 3.55
26 - 3.73
27 - 3.31
H9 - 3.55 Limited Slip
B6 - 3.73 Limited Slip

 

it really doesn't matter what gears you have in the rear. You are going to need new gears to run those big dawg tires you are talking about. Your truck would more than likely be shifting all the time on the freeway and you are goign to notice a huge lose of power sot to mention that your steering component are going to wear out faster and your brakes will to. Why so big on the tires anyway, do you have a big lift?

 

a 37" tire is really not all that heavy actually i think a 36x14.50 is a heavier tire plus i like the 37x12.50 look and i know what its like to run big tire with a tall gear ratio but i looked and i have 3.73's so im going to go with the 37's ....but thinks for lookin out and i know what im getting into ....btw it's running a 3'' BL right now and the 4" susp. is on the way

 

Clint,

What, Crazy4Fords is refering to is the power curve of your engine and the way the transmission will behave if you put 37" tires on. For your transmission to shift properly and for the engine to feel as it does now, after the tire change, you'll need 4.92:1 gears.

Changing the size of the tires effectively changes the gear ratio.

 

yeah i know about outer diameter and engine RPM and maybe i'll just go to a 36'' but who knows ..thanks for your input