gearing after lifted jeep

so im about to put a 6" lift on my XJ but i have heard so much about needing to change the gearing after it is lifted...what does that mean, the gearing and all?

does it have anything to do with the speedometer and mileage meter being incorrect now that larger tires are on it and needing to correct that?

The only gearing change you will have to do that I know of is for the speedodometer after increasing the size of your tires, which normailly happends after you lift.. And with a 6" lift you are probably going to be putting on some BIG tires...YES.

You might want to regear the axles as well. I put a 5" lift and 33inch tires on my XJ and it could use a deeper gears. The XJ doesnt accelerate as well as it use to. Plus the added weight on of the new tires doesnt help. What axles are you running? If you have a Dana35 in the back, you might want to look for a Dana44 out of a 87-89? XJ. The Dana35's are weak axles that tend to break. You can wheel with the D35, just go easy on the skinny pedal....

Pic of my Jeep:
http://img.photobucket.com/albums/v491/Pstrkd4brthcntrll/Tires5.jpg

If you get a "Gears&Rears" catalog, or a Q-tec, they have a chart with what gears are best for your tire size and application.
From my experiance 33's need at least 4.11. if you want to wheel it 4.56 is better.

I agree with these guys but it all depends on what your doing with your rig if your wheelin it you for sure need two look in to some gearing swaps but as well if your doing little trail running and nothing hard core your stock dana 35 will last for awhile but if you are getting in to hard core stuff then you should look in to up grading to a dana 44 atleast. if your just lifting it for the looks and it won't see to may trails then 4.11's will do you just fine. but back to your first question about why change gears, because if you stay with stock you will lose at lot of performance as far as acceleration goes and it will over work your tranny causing it to wear out faster