Yup that's correct. Id go with the 4.10s if that's your answer. You probably won't even notice the .1 difference from the exact conversion so it will accelerate just like it did with the stock setup

 

I'm getting 16 or better.

 

I used to have an 06 gmc with 3.43 gears, normal for these trucks was 3.73. The difference in gears was 5 mph higher shift difference in each gear. So instead of shifting into overdrive at 65 it would go at 70

 

Mathmatically that is correct, but you aren't taking into consideration that the weight difference between a 29" tire on a stock wheel vs. A 33" tire on a wider wheel is not proportional to the math in your gear calculation. 4.10's and 33's will not give you the same pep that 29's and 3.55's do.

 

Very true very good point. But 33 inch tires on a jeep shouldn't be too much extra over stock to go to the extreme. The theory counteracts itself bc the little extra weight does need a little more pep but with even lower gears your rpms will be slightly higher using more gas. The gearing all depends on your intended use, crawling or dd. Also loading your jeep with 4 grown men averaging 200 lbs is a big factor but most people won't go with lower gears bc they have extra people weight. If you are going to a mixch bigger load range tires then you will have quite a difference in tire weight but there is no need for a heavy duty tire on a jeep

 

i run 4.10s and 33s. if i were to do it again i would do 4.56s. not saying the 4.10s are bad though.

 

~14 city, ~19 highway

 

Do it

 

Agreed

 

What name brand gear does everyone recommend I hear the usa standard is loud.

 

On the mpg thing gearing really does not make a difference if you stay reasonable. Anything from 3:55 to 4:88 from 31 to 35in tires are going to net you about the same MPG or can rather.

Its all in your driving style.

Just because your engine is reving more does not mean its using more gas. Its motor load that matters.

the heavier tire the less mpg you are going to get. The heavier foot you have the less mpg you are going to get. Gearing really is not going to make a difference in this situation.

 

Do you use your XJ for DD?
Does you use it to tow?
How much highway does it see?
Extra weight on the truck? (Bumpers, winches, etc, etc)
What kind of wheeling do you do?

If it's a DD/weekend warrior (depending on what kind of wheeling you do) 4.10. If you don't see a lot of highway or use it to tow often, or perhaps live in the mountains I'd go 4.56, if it's not your DD and you got a lot of extra **** in the rig I'd go 4.88

Just my .02

 

Just to add...

I run 32s with stock 3.55s currently and I'm thinking of going 4.56 because I live in the mountains and hills are killer lol. Don't see much highway but even with that combo I think 65-70mph would be tollerable.

I'm guessing this would be similar to a stock XJ with tow package (29" tire and 3.73 gears)

 

If you have a 4cyl donor XJ (pullin out the stock 4:10's) and gettin them bargain, then 33 with 4:10's is great. If your buying them new (bigger bucks than a donor) anyway, then get the 3.50++ with the 33's.