resharp001

I can't speak to the the XJ at all.....similar tranny? I have a friend on 35" Nitto Ridge Grapplers/4.88s/3.6L. We are pretty close to the same on the highway....and he has similar feelings. Just on the aggressive side for him. But, as you already mentioned....there are a lot of other factors. Geographic location and altitude, jeep use, towing possibilities, weight, tires, tire pressure. I'd say most of it just boils down to actual tire measurement at whatever your normal inflation is, and gear ratio. If you want to see what cruising around at 3k RPM is like on the highway, just downshift till you're right there. At highway speeds it's easy enough to see those differences. It's lower end shifting and acceleration you can't really replicate easily.

Oh, and just in case you were wondering....I did not regear from 3.73 to 4.10...that was in the process of an axle swap that had nothing to do with gearing....it was just a byproduct. I'll bow out and let others respond.

JKSlow

Agreed - I have a 2012, 4.88's on 37" Toyos with an auto, but before that I ran those same gears with 35s for about a week and hated it. Around the city it was awesome, but on the highway it was screaming.

Edit - Mine is a 2 door so its lighter than a JKU, but it is loaded down with armor.

scubatech

Overdrive in XJ is close to .69. Overdrive in 2014 is .80. The high passes in Colorado suck the power out of even a powerful V8. I run 4:10 in mine but even with those I can feel an 11000 ft. Climb. But I like running 80 MPH on these open roads. Everything's a compromise.i

Fafafofi

I'm in the market for a newer jku with a 3.6L. Most of my miles will be highway but occasional trips to higher country. I already live in the mountains. Will 3.73s compared to 4.10s be much different with bigger tires. I imagine I'll go with 315/70/17 Duratracs again. I have my eye on a Rubicon but the tag says 3.73 gears. I thought all Rubis had 4.10s

AnvilX14

I have a 2014 JKUR with auto trans and 4.10 gears, I ordered it that way. For the first 3 years I had 35" Federal Couragia MT tires and freeway driving in Michigan was bearable, but at 70-75 I would have to set the cruise and then bump it back 2 clicks to get it to shift into 5th gear to run around 2700 rpm. Then, with any hint of an uphill stint on the highway it would downshift to 4th and be at about 3100 rpm. I haven't regeared but I have moved up to 37s. I think regardless of witch of those two tire sizes I have, I would go to 4.88.

scubatech

I think most Colorado Dealers order 4:10 ratio but lower elevation Dealers may not. There is about 200 RPM difference and you can notice it but for the money go 4:56 for 35" tires. You would turn about 2700 RPM at 70. I turn 2400 with the 4:10 ratio.

resharp001

Fafafofi is looking at a "newer" used jeep (per another thread), but for people looking at brand new jeeps on the lot......if you have ANY plans to go with 35s or larger, you're better off putting your money towards an aftermarket regear than you are spending $600 or what not on the upgraded factory 4.10s (or for a sport/sahara upgraded 3.73s).

jordy

I posted up in your other thread. According to the VIN it left the factory with 4.10's.

If you're going with anything other than a Rubicon, save your money for the front axle upgrade. If you're going with a Rubicon and over 35's, save your money for the front axle upgrade. May as well do the rear at the same time at that point and be done with it.