I have a 2015 JKU with a leveling kit and I've also trimmed the flares so I have room for 35's. Currently on 33's (pic attached).

What are people's experiences or thoughts on going with 35's without regearing?

 

If you have 3.73 gearing it is tolerable. If you have 3.21 gearing, most people on here over the 8 yrs I've been on this forum say it sucks. Significant loss of power. Manual transmission 6th gear becomes completely useless. I don't know what the percentage is, but I assume 80%-90% of all Jks and jkus built over the last 8 years have the crappy 3.21 gearing. I ordered my 2012 Jku to get the 3.73 gearing. Last fall I traded my 2012 for a 2014 jk and it took me a very long time to find one with 3.73 gears.

 

How can I know which gears I have? And my JKU is the 6 speed manual.

 

Two ways. One is to get your original build sheet. There is a website you can find where you put your VIN and it will get you the build sheet. Another way is to jack both back wheels off the ground and spin your back tires by hand and count how many revolutions your drive shaft makes. I don't now the formula, but others on here may chime in.
There's a good chance you have 3.21s. Do a search on here for 35s with 3.21 and I think you'll find the info I was talking about. As I stated before, if you have the 3.21 and go to 35s, your 6th gear will become useless. It just is not an an RPM band at highway speeds that has enough horsepower to maintain the speed.

 

I have a 2016 JK with the 6 speed manual transmission - and my truck came with that horrible 3.21 axle ratio, and yes - it sucks balls ...

Go to your local dealer’s parts dept. with your VIN - they should be able to tell you everything that is in your truck.

Failing that, get your back wheels off the floor, mark your rear drive shaft with something - then count how many times your drive shaft revolves with one revolution of your rear tire.

E.g. If your drive shaft spins just over 3 times with one revolution of your tire, you have a 3.21:1 ration.

Neville

 

Oops -

Sorry Rob, I was writing my reply as you posted !

Neville

 

I've tolerated 35's with the old 3.8 for a while now with the 3.73 gears. You certainly wouldn't notice it as much with the newer motor as long as you stay away from the heavy tires and avoid trailer pulls up through the mountains. Check your tire weight now and shoot for a low number when you upgrade.

 

Finally found a place to get my build sheet using my VIN. Of course I have the shitty 3.21 gearing ☹️

For those looking for their build sheet, here is a good link:

https://fcacommunity.force.com/RAM/s/equipment-listing