Best Gear Ratio For Larger Tires (Jeep Gladiator & Wrangler JL) | Inside Line 

That sounds like an awesome set up!

I have the same…a 2024 XR it’s amazing!

Yeah you got a nice setup that sounds fun as hell

Wish I got that kind of mileage as I'm running the same tire on Black Rino Arsenal wheels with no lift..🤔

One of the good things about the front axle disconnect is that you can throw a lot of caster at the front axle and it won't make a difference with the driveline on the highway. If you are worried about the front driveline hitting, I would recommend unloading your suspension fully to ensure that the shaft isn't contacting the front crossmember. For the rear driveshaft, you may find that you need a carrier bearing drop to prevent the driveline from vibrating. I haven't had to do this with my Gator Gladiator, but my flatbed Gladiator on 1-ton axles has aftermarket drivelines from JE Reel that take care of that issue.

@@DrivingLine roger. Thanks man. Super helpful.

I would go 4.88. The difference between that and a 4.56 is fairly minimal. The extra gearing will help compensate for the added parts better than the 4.56.

I don’t think you’ll need to regear with just a 34-inch-tall tire and the EcoDiesel. A 4.10 wouldn’t be worth the cost and a 4.37 might be too much gear if you are doing a lot of interstate commuting. From the small group of people that I know with the EcoDiesel, changing the differential gearing isn’t necessary until you get to a 37 inch tall tire.

I don’t have much experience with the diesel platform in the Gladiator. I would opt for 4.88 or 5.13 to keep the engine RPM lower on the highway.

@@DrivingLine thanks

Zero offset/4.75 inches of backspacing.

@@DrivingLine good deal! So no rubbing issues? I’m running a +1 (5.00 backspacing) was just curious if I could run a 38x13.50

The only rubbing I experienced that was an issue was with the stock front bumper. I have since upgraded to a stubby front bumper and it’s not a problem anymore.

If you plan on going to 40’s, I would go ahead and go higher than 5.13. You’ll rev a little higher initially on the highway with the 37s, but you’ll be happy you did it when you move up tire sizes.

I honestly don’t have a lot of experience with the eco-diesel in the Gladiator. I believe Nitro Gear offers a 4.37 gear that is intended for diesel JTs and JLs with 37s. I would say 4.88 would be more than enough.

Your RPM's will stay lower with the 5.13s, which will help with fuel economy.

The suspension lift impact is fairly small on the Gladiator. The aerodynamics are already terrible. The tire size, weight, and additional gear are all way more important in my experience. I’ve had multiple lift sizes on both of my Gladiators. It’s always been the tire size that made the biggest difference. Gator colored Gladiator in the video has 3 inches of lift and 38s for reference. Before that, it just had a 1 inch lift and same tire. MPG and performance was the same.

When I had the 38s on my 392, I definitely felt like it could’ve used a little bit more gearing than the 4.56. I know there are a lot of guys out there that might disagree with me on this, but I think the HEMI’s actually work better with a little bit more differential gearing. I don’t think I could justify re-gearing from 4.56 to 4.88. However, if I had your setup, I would probably move to a 4.88 gear. Especially at that elevation.

@@DrivingLine yeah I agree I think I would enjoy the benefit of a 4.88 I have thought about it as well, I just wasn’t sure if i wanted 4.56 or 4.88s but 4.56 is would probably not be a big enough difference to make the work/install worth it

I have 4.56 gears in my 2021 Wrangler 392 on 37’s and I think the gearing is perfect. The diesel would probably be better served with a 4.37, but I’m not sure if that Nitro Gear is still available. My approach with the 4XE would be similar to the 3.6L. It will benefit then most of those three platforms with higher numerical gearing. This is especially true once you zap the battery pack and you are running on gas only. I would prefer a 4.88 in the 4XE. Maybe even a 5.13 depending on build setup and elevation. For a while, you couldn’t program higher gear ratios into the 4XE. I believe they have this sorted, but I remember seeing it being limited to certain ratios.

@@DrivingLine Is the rationale on why you would choose 4.37 for diesel is rooted in the fact that it has too much low end torque? If thats the case that applies to 4xe too.. there is too much torque all at once and high numeric gears might get chewed esp given overall weight of the vehicle being close to 6000lb. When you zap the battery to 0% there is 20% reserve capacity set aside for normal hybrid operations - at that point the 4xe is just like a toyota iforce-max parallel hybrid and its "always" a hybrid producing the spec-ed Hp and Tq irrespective. The only time you will run the battery to excessive depletion and limp mode is if you are towing something uphill for a long stretch somewhere in colorado where the speed at which the demand is sipping out battery exceeds the speed at which it can regen (since you wont have any regen activity if you are constantly uphill). Apart from that edge case, you are always 370hp and 470tq.

The diesel rationale is simply to keep the RPMs lower. It makes plenty of power at low RPMs and will retain fuel efficiency that way. My experience with the 4XE is more limited. But, based on the powertrain, shops I work with, and experience conversing with 4XE owners, the general consensus is that airing on the side of more (higher) differential gearing is better.

You generally need a little more gearing with the 3.6l and the manual. For example, a if I went 4.88 with an automatic, I would want 5.13 with the manual.

The last two modern diesels I owned had enough issues to make me never want to own another emissions equipped diesel again. For me, reliability is more important than fuel economy. To be clear, I’m not saying what you have is unreliable. I’m just saying my experience with the emissions equipment on these modern diesel engines has been terrible.

As someone who currently has two Jeep Gladiators and two Wranglers 392’s, I sympathize with this remark more than you know. 😂

My experience with the manual and 3.6L has always been you want to go up one numerical gear set from what an automatic would be. For example, if an automatic would go with a 4.88, the manual should go with a 5.13.

Isn't 1st gear for manual is ~3:1, while 1st gear for auto is ~4:1?

The six-speed in the Gladiator has a 5.13 first gear ratio. The 8spd auto is 4.71.

I believe the benefits of changing out the differential gearing outweigh that potential risk. I’ve been wheeling my Gladiators for years, and been on a lot of trips with other Gladiators and JL Wranglers. I’ve never personally seen a ring and pinion failure on either platform, but I’ve seen a lot of axleshafts break. I think that’s the bigger concern.

I would go 5.13. I’m just not convinced that the pinion on the 4.88 vs 5.13 makes that much of a difference.

@@DrivingLine I put 5:13’s in my 09 Sahara and run the same tires and have chewed up that Dana 30 pinion so many times. Been building super duty axles since 2020 haha to fix that. Guess I haven’t chewed up the rear Dana 44 pinion so should be safe right? Haha.

The Dana 44’s in the Gladiator are fairly robust. Aside from the FAD, I don’t think you would have much issue running a 37. They are much stronger ring and pinion wise over the JK Dana 30 for sure.

@@DrivingLine 5:13’s this then, didn’t think about how much more robust the new axles are. Great video like always. 👍🏼