Trying to find out what axle ratio I have. I didn't buy my Jeep as new, so not knowing how it was delivered. It's a 07 Unlimited Sahara 4-door w/auto, don't think it came with the tow package because it had a tow hook on back, not a hitch. I though the auto came with the 4.10 and the stick with 3.21, but I could be wrong. How can I check this on the Jeep, meaning by looking under to eye balling it. Want to know because will be getting new tires very soon, and want to increase to a 265/70R18 or 275/70R18 and don't want a large power/mpg loss. Thank for any help you all could give.

 

get both rear wheels off the ground rotate the wheels and count how many times the driveshaft rotates. i.e a little over 3 = 3.21 a little over 4 = 4.10 etc. good luck

 

call local stealership with last 8 of vin and get a build sheet. more of a headach then lifting the rearend but takes less time.

 

2 full rotations of the tire, not one.

Quick and easy. Just mark the tire/ground and the driveshaft/flange. Spin the tire 2 full revolutions and count the number of times the shaft turns. (chock the tires and put in neutral. Then lift one tire and spin. If you do the rear, take off the e-brake also)

 

Email Chrysler customer services with your VIN number, and ask them to send you a build sheet. I did, and found out all sorts of cool stuff including gear ratio. I emailed them through a link at jeep.com.

 

That's if you only lift one wheel and turn it. The differential doubles your ratio. If you lift both wheels and turn them in unison, you should only need to turn it one revolution. (right?)

 

The best way to get this info is by sending your VIN to Jeep, from this website, and they will send you your build sheet. I had to do the same thing, because I also didn't by my Jeep new, it took them about 1/2 a day to email me the info back. Hope that helps.

http://www-5.jeep.com/wccsapp/univer...ull&category=U

 

actually '07's with auto had 4.10, not 3.73...

 

Good to know, I've only done it with one tire off the ground, and didn't consider that it would be different for both tires up.

 

Thanks for all of your quick replies. I emailed Jeep.com to get the build sheet, no reply yet. I also called the Jeep dealership with the vin. and told me they could look it up on their system, but couldn't print out a build sheet. They said it had a 4.10, I never thought to call them because their not so helpful for the most part.
Can't wait to see the build sheet , and any cool info it might have.
Now for my follow-up question, since it seems to be a 4.10 ratio. Which tire size should I go for? The 265/70R18 or 275/70R18, the jeep is pure stock. It came with 255/70R18 and I will be using the stock wheels. If needed I can add some wheel spacers, but a lift will be far down the road. Any thoughts ?