After putting a small lift on the Jeep it feels as if your using quite a bit more right foot getting the thing up to 75mph and holding it there. Not attempting to win any races here, but it just seems odd that a small lift would increase aerodynamic drag that much slowing the vehicle. Anyone else notice this and if so what can be done to make it more efficient at highway speeds. The XJ needs to be a DD as well as a toy for the time being.

 

It does increase drag, but if you increased tire size you lost the torque multiplication of the final ratio too.
It also takes more power to keep those larger tires turning.
Thus the reason you need to re-gear, so if you got 3.07's and go to 31x10.50's you would want the 3.55's from an automatic just to get back to the equivalent ration you started with stock tires.

 

i have the same problem...i have a 2" lift with 30" tires

 

2" and 30" tires is not much and I wouldn't think you should notice it there.
My XJ is a standard 5 speed, and with 3" lift and just 235/75/15 atm (inbetween jobs so no buying new 31/10.50/15)
I rarely use 5th gear, but with 3.07's its very high geared anyway.
I got an Automatic XJ for parts and I plan on swapping both diffs with mine for the 3.55's so the 31" tires will keep it very close to the stock tire RPM.

 

Gears would be the way to go, but unless you plan on staying exactly the same for the rest of your truck's life a set of 3.55s will kinda be useless. I'd suggest getting 4.10s at the minimum.

 

Doh! and here I started with an auto transmission.

Don't think I'd go with larger tires so what gears would be appropriate for 31s

 

Get 4.10s and you'll be happy.

 

I'm on 5" with 31s and the 3.07s don't bother me much. Don't plan on regearing until I go with 32s.

 

I do pretty good with 32's on either 3.55 or 3.73 gears. I forget which one I have in my XJ

 

3.55s are stock for some, I think for autos, but I could be wrong.

3.73s would be a great balance if you are sticking with 31s.

 

im stock with 3.55s, if i go higher where does that dabble into messing with the speedometer and throwing off MPH?