I'm running 35 BFGs and I BELIEVE that I'm still running the stock 3.55 gears on D30/8.25 combo and it's pretty bad on the highway for maintaining speed and I just want to upgrade it.

My XJ is a DD and a weekend warrior but it's mainly a DD so I need a ratio that compliments a lot of highway driving which also is effective in wheeling. I've read some articles on the issue and they all say to go with the lowest gear that I can, which would be 4.88, but I don't know if that would compliment highway driving very well.

So, either 4.56 or 4.88 for 35" on D30/8.25?

I'm running 4.56's on 35's and it's nice and doable, but I like to speed and the 4.88's would probably be even better. I drive at least 70 miles a day.

Get a transmission cooler.

Id say go for the 4.88s. And x2 on the trans cooler. I've had a stock zj cooler on mine for a while and it does good. But im about to put in a bigger one from an explorer.

4.88s.

4.56 if you want it to be the same as stock. 4.88 if you want a little bit more umph. But you will be running a higher RPM at highway speeds with the 4.88

5.13 gears you have overdrive use it

they don't make 5.13s for the 8.25

oops go with 4.88 then

Automatic, 4.88
Standard, 4.56

Yea, I've definitely decided to go with the 4.88s. I don't have the money for them just yet, but they are priority numero uno. Now to find somewhere that sells the 4.88 kit....

http://www.seriousoffroadproducts.co...ing-And-Pinion

http://www.seriousoffroadproducts.co...Chrysler-76-Up

You're gonna need both R&P's, master install kits, and a new carrier for the 30 to accept the numerically higher gears.

http://www.seriousoffroadproducts.co...rse-4.88-Ratio

http://www.seriousoffroadproducts.co...-Dana-30-Front

And beer.

Got a link to that?

Mmmmmmmmmmmmmmmmmmm...
Beeeeeeeeeeeeeeeeeer!!!!!