I have 3.73s now, and I run 33's. If I just bump to 4.10 and 35s will it be close to the same as my setup now? Over on the other place, they are saying 4.88s to 5.13....but damn, on the highway my rig would be revving 3000 plus RPM in overdrive. NOT what I am looking for. I want to stay close to the setup I have now, as it drives fine etc but damn, 35's are calling my name and I just want it to drive, accelerate and get similar milage to what I get now.
Gearing question for JKU
- Thread starter kojackJKU
- Start date
Check out http://www.grimmjeeper.com/gears.html to compare tire size and gears. Enter your current setup on one side and new setup on the other and it will allow you to compare rpms at different speeds to get similar performance to your current setup.
Kmrtnsn
Explorer
If you have a Dana 30 up front I would not run anything bigger that 4.56. Once you get into 4.88 5.13 territory with those spline counts and the size of the teeth you're just asking for a failure.
I'm currently running 3.73s and 33s and will eventually go to 4.56 as I think there isn't enough difference between the 3.73 and 4.10 to justify the cost.
Find your stock tire size and rpm on the chart above, then find your 35s and compare.
I'm currently running 3.73s and 33s and will eventually go to 4.56 as I think there isn't enough difference between the 3.73 and 4.10 to justify the cost.
Find your stock tire size and rpm on the chart above, then find your 35s and compare.
KojackJKU - Glad it helped.
Kmrtnsn - I daily drive 35" tires, 4.88 gears on my Dana 30 and have not had any problems with the gears. I've been running them for over 50k miles. I switch to 37" MT when I go wheeling and have a locker in the Dana 30 and the gears have held up fine. Ball joints and tie rod ends have been a differtent story.
Kmrtnsn - I daily drive 35" tires, 4.88 gears on my Dana 30 and have not had any problems with the gears. I've been running them for over 50k miles. I switch to 37" MT when I go wheeling and have a locker in the Dana 30 and the gears have held up fine. Ball joints and tie rod ends have been a differtent story.
I have the ball joints and TR's done. I don't see how revving higher on the highway will yield better gas milage. that's why I am going with 4.10. It will drive the same as if I have the 3.73s and 33. Plus, I have the superchips to give me any extra ommph I need. I am not doing a gear swap for more power, just to keep what I have now the same while moving to new tires.
The idea is that you'll be in your ideal power band more often instead of below it (or having to gear down and going above it). If you have a lot of hills in your area (or its very windy), this would be more of an issue. If it's flat (and not super windy) then it doesn't help at all. I eaked out 26 MPG over a tank once in my 2007 JKU (6spd, heavy bumper, 2.5" BB, 33s, 3.21s). But it was all flat and overall was downhill (heading to the cost), and wasn't windy. That was a great leg. But once the wind picked up or I would get into the hills I didn't have deep enough gears to stay in 5th gear and my mileage went to ****.
Whether you have an auto or a 6spd will make a big difference as well. It's much easier to compensate for poor gears with the 6spd. With the auto it's much more important that you get it dialed in correctly.
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I have an auto. and Yes, in the wind My milage does suffer. but it does in every vehicle I owned. I am averaging 20 mpg highway during trips. I probably drop to 18 - 16 in strong wind. I do live in a place with hills etc. and for the most part, my jeep drops to 3rd some of the time up them....but its only an issue when its going to 2nd which is most of the time, never. UNLESS.....I am driving fast. Different story then. But. Even dropping a gear, I'm not revving 3000 rpm where all the GEARING nuts say to run in 4th. I don't think so tim.
If your going to 35's then I'd say 5.13. I ran 5.13's for a long time on 33's and was not happy at all, mileage or performance wise. But once I put 35's on it it felt perfect. That put my rpms at 2500 or so at 70mph. 65mph was the sweet spot at 16mpg. Honestly though, if your looking for mileage/range, leave it the way it is now...
35s with 5.13 at 100/60 isn't 3000 RPMs (or anywhere close to that), but ~2380 (will vary slightly depending on the exact size of the tire - higher if the tire is smaller than 35"). 4.88s would be ~2260.
4.88s might be a better option if you're not going to run true 35s. But from what many many people have said... 3.8L, auto and 35s... 5.13 is the sweet spot.