Stuka

One thing people need to remember is the differences in transmissions.

35's with 4.88's with an 07-11 automatic is perfect. However the same tires and gearing with a 6sp means you are going to be running a lot more RPM on the HWY as the overdrive in a 6sp isnt nearly as high as it is for the 4sp auto.

For '12+ rigs they have a 5sp auto, and again the transmission gearing is different.

Most charts do not take into account the transmissions overdrive gearing.

a4x4high

So Maybe what we need is for a few guys who are running 35's and 4.56 and 4.88 ,go get on the highway and run at 70mph and let us know what the rpm is mayb do 3 different speeds 65,70 and 75 so us guys who are getting to regear have an ideal of what we will be running with the two gear choices from real life nimbers instead of mathmatical equations.

JPop

The charts in the FAQ certainly make provisions for the differences in automatics and manuals. They are also specifically created with the JK in mind.

https://www.jk-forum.com/forums/modi...17/#post211276

JPop

If the person providing the rpm numbers have measured their tires correctly, the rpms from the chart in the FAQ will be very close, ±2%.

msykes

I have a 2009 6 speed. I just installed 4.10's and bought new 315/75r16. The tires measure 34.5" with my trusty tape measure. The 4.10 gearing brings it back to a little over stock power levels with about 10 extra ft/lbs torque. So far this setup has been great for me, I live in an area with mild hills. When I go up to the mountains, they're just a little too low for 6th gear running, so I downshift to 5th (except one mountain had me in fourth). Anyway, 4.10 is expensive to the tune of almost 400$ each set; 4.56 is cheaper at ~225$. I'm completely happy with the 4.10's, but I'm considering going to 4.56 for a little extra power.

Also if anyone is interested I have an excel spreadsheet that will let you play with the numbers and see how different tires and gears will perform.

Flyer

I have 4.10s in my 2012 JK. I will eventually go to 35s and regear since I live in Colorado. I'm pretty sure 4.56 will be perfect and will not go higher, but 2011 and older Wranglers seem to like 4.56 and 4.88 here.

Flyer

Pablo, if you are running Toyo MTs, those are really heavy tires. Not sure about their ATs. That is the only reason I stay away from the Toyo and Nitto MTs on my Jeep. They are fine with torquey V8s but suck the power out of our Jeeps.

Ryan0260

Actually they aren't that bad if you are geared properly

jimk403

When our tires were new, they measured 34.75". Somewhere in a previous thread, I posted a pic of my dash at 70mph and rpm's at 2600, which for our terrain, elevation, towing, etc is just about perfect.
No gear ratio is going to be ideal from one driver to the next, and don't believe everything you read on internet forums.

Makeitwork

Pretty new to this.. And just trying to make sure, since it falls in line with the subject here.. Got a 2012 6 speed Manual 4dr with 3.21 gearing.. Planning on getting 33-35" tires (not sure which yet preferably 35)".. Best performance gearing for usage of daily driving *Highway* and occasional off-roading the 4.56's would be ideal? or is 4.1 just enough? I've been researching the different variables and everything to get the proper gearing within this tread, including the charts posted, but I feel as if I just need this answered directly. I'm too confused on the subject. I am concerned with gas mileage as well as I am doing 17.5 mpg.. Would I have to sacrifice one of the other to get exactly what I'm looking for, in terms of acceleration and towing power and fuel economy. or is there a way to obtain a bit of both..