where at what kind of speed scencor do I need to get if I wnat to go from 30x9.50 tires to 33x12.50's

 

You need to change the speedometer gear in the transfer case, they are pretty expensive AFAIK...Tj
Here is a link I have
http://www.jeep4x4center.com/jeep-sp...BForum%2B10off

 

what is the stock gear ratio for an np231 transfer case?

 

GEEZ! $80!!! Might as well buy a cheap gps just to use as a speedometer.


I think this has the info you want.

http://www.naxja.org/forum/showthread.php?t=101238

 

2 hi or 4 hi your at 1:1, 4 lo 2:72--- doesnt matter , you need to know what ratio your diffs are and the exact dia. of the tires you are going to run. 31-10.50/15 tires are not always 31 inches tall! Measure from center of wheel to outside edge of the tire and multiply by 2 for dia. There are several charts online to determine what tooth count you will need... I have 31s w/ 4:11 gears and bought a 38 tooth pinion for the speedo from the dealer for less than 15 dollars. A 39 tooth would have been 68 dollars!!! Do your math and shop around, you can buy used drives online for 25 dollars..

 

have someone drive next to you figure out the difference simple,cheap