My name is Bill, and I am from NH. I have been lurking for two years this month. Could not strike a decent deal with a JK, so I got a Silverado. It has been a great truck, but last night I traded it in for a 15 Unlimited 6 speed Anvil grey. So far, it is everything I wanted and needed. At some point someone upgraded the wheels and tires to 255/17 BFG Mud terrains. I love it so far. It will be hauling my side by side too. Just need to figure out if it has 3.21s, or 3.73 with the tow package. And I need to figure out if the computer was programed for the bigger tires.

 

You can type your VIN into this Jeep database and it will tell you what options that your Wrangler came with.

https://jeep.custhelp.com/app/jeep/e...aHRtTEZFUW0%3D

Your speedometer can be check pretty easily with a GPS app. I tuned mine pretty close with the Superchips programmer.

 

Welcome! Nice Jeep.

As Jeremy said you can use your speedo to determine if the tire size was reprogrammed. To check which gears you have, jack up one rear wheel. Make a mark on the wheel and the driveshaft. Rotate the wheel two full revolutions and count the revolutions of the drive shaft. Just under 3 and a quarter turns will be 3.21s. About 3 and 3 quarter turns would be 3.73s etc..

 

Thanks guys for the advice. I was not sure on the gearing since there was a hitch, but according to Jeep, there is a tow package with just the hitch, and the connector, and then there is a max tow package with 3.73s. I did not see a tag in the usual place on the front, or rear diffs. But it turns out to be 3.21s with an open diff out back according to the site you posted JeremyB.
As for the speedo. According to my GPS, it has been adjusted for the tire size difference. So I am good to go.

 

Welcome aboard!

 

Welcome to JK-Forum Bill!

 

Glad you're homing in on the details. Just remember, when buying a used vehicle what is on the build sheet is not necessarily what you got. It's one of those "trust but verify" kind of deals. Prod, poke, spin. It will get you there.