Wanting to go to 40s

[AtlJeeper1629]

Merry Christmas everyone!!

I currently have 37 in nittos and will be replacing them shortly after the new year. I’d really like to go to 40s for height and look. My jeep is a 2020 JLU Rubicon. Gears and axels are stock. It’s got a 2.5 inch lift already. I know gears will have to go to at least a 5.13 I think. Will I need to add more lift and upgrade Axels?

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[wibornz]

A 2 1/2 inch lift will not clear 40 in the back so trimming or a bigger lift and drive shafts will be needed. Expect to upgrade all of your steering component. The axles will be okay if you don't wheel it. If you do wheel it. Plan on putting one tons on or, spending a bunch of money to upgrade the axle shafts and truss the axles then eventually go to one tones anyways. Also with the stock brakes on the Dana 44, you should upgrade all the brakes.

I ran 40 for a little bit. The tires are truly the cheapest part of the equation.

 

[chevymitchell]

The tires are truly the cheapest part of the equation.

^truth.

Pandora’s box of mods.

 

[Gorilla57]

To the OP...You’ve been on these forums since 2020, plenty long enough to have read the numerous threads on 40’s and requirements. It’s an expensive step to make, but plenty have done it and have documented how to do it. ??

 

[AtlJeeper1629]

To the OP...You’ve been on these forums since 2020, plenty long enough to have read the numerous threads on 40’s and requirements. It’s an expensive step to make, but plenty have done it and have documented how to do it. ??

If it bothers you that much that someone posts looking for advice, why you read or respond. Keep scrolling and save yourself the headache. Merry Christmas!

 

[Whaler27]

A 2 1/2 inch lift will not clear 40 in the back so trimming or a bigger lift and drive shafts will be needed. Expect to upgrade all of your steering component. The axles will be okay if you don't wheel it. If you do wheel it. Plan on putting one tons on or, spending a bunch of money to upgrade the axle shafts and truss the axles then eventually go to one tones anyways. Also with the stock brakes on the Dana 44, you should upgrade all the brakes.

I ran 40 for a little bit. The tires are truly the cheapest part of the equation.

This.

Going that big also makes it harder to find and keep decent drivability on the highway. Lots of leverage trying to pull your jeep apart, especially if you‘re wheeling it.

 

[wibornz]

^truth.

Pandora’s box of mods.

I remember the day that I went back to 37s. Sitting in the garage, cut off wheel in hand, the tub of the Jeep taped off where I was going to cut the tube of my then newer JLUR. Thinking if I do this, I am never going back and cutting the tub is a $25,000 to $30,000 commitment to run 40s. I pondered for a few minutes with the cut off wheel in hand and said to myself, for the wheeling that I have done, think Rubicon trail, Pritchett Canyon, Holy Cross, and so on with 37s and all the extra fuel and maintenance that goes with running 40s is it worth it. I pulled the tape off, put the grinder away, jacked up the Jeep, put the 37s back on, and listed the set of 40s for sale. 37s have been hard enough on the Jeep. My fourth locker is not functioning right, I have been through two sets of 5.13 gears, one set of rear axle shafts, put RCV axles in the front, replaced the ball joints, and all the front steering components. Yet I am not done. I will be ordering a Fusion 4x4 60 for the back in about two months. I have found that the Dana 44 will not hold up to the amount and type of wheeling that I do even with 37s.


Just the price of wheeling. If I was on 40s, I would also be dealing with a 20% loss of mileage too. The loss of mpg is a big deal out west. I pull a camper all over the US and there are places out west that I would not have enough fuel to get from one gas station to the next gas station. Pulling my camper with 40s, the best I would see is 8 mpg.

 

[Gorilla57]

If it bothers you that much that someone posts looking for advice, why you read or respond. Keep scrolling and save yourself the headache. Merry Christmas!

Nope, doesn’t bother me. Just sayin’ there’s plenty of threads on this subject. Happy reading. ?

 

[AtlJeeper1629]

I remember the day that I went back to 37s. Sitting in the garage, cut off wheel in hand, the tub of the Jeep taped off where I was going to cut the tube of my then newer JLUR. Thinking if I do this, I am never going back and cutting the tub is a $25,000 to $30,000 commitment to run 40s. I pondered for a few minutes with the cut off wheel in hand and said to myself, for the wheeling that I have done, think Rubicon trail, Pritchett Canyon, Holy Cross, and so on with 37s and all the extra fuel and maintenance that goes with running 40s is it worth it. I pulled the tape off, put the grinder away, jacked up the Jeep, put the 37s back on, and listed the set of 40s for sale. 37s have been hard enough on the Jeep. My fourth locker is not functioning right, I have been through two sets of 5.13 gears, one set of rear axle shafts, put RCV axles in the front, replaced the ball joints, and all the front steering components. Yet I am not done. I will be ordering a Fusion 4x4 60 for the back in about two months. I have found that the Dana 44 will not hold up to the amount and type of wheeling that I do even with 37s.


Just the price of wheeling. If I was on 40s, I would also be dealing with a 20% loss of mileage too. The loss of mpg is a big deal out west. I pull a camper all over the US and there are places out west that I would not have enough fuel to get from one gas station to the next gas station. Pulling my camper with 40s, the best I would see is 8 mpg.

Wow!!! Thanks for your input. I don’t want those problems!! ?

 

[Zandcwhite]

I remember the day that I went back to 37s. Sitting in the garage, cut off wheel in hand, the tub of the Jeep taped off where I was going to cut the tube of my then newer JLUR. Thinking if I do this, I am never going back and cutting the tub is a $25,000 to $30,000 commitment to run 40s. I pondered for a few minutes with the cut off wheel in hand and said to myself, for the wheeling that I have done, think Rubicon trail, Pritchett Canyon, Holy Cross, and so on with 37s and all the extra fuel and maintenance that goes with running 40s is it worth it. I pulled the tape off, put the grinder away, jacked up the Jeep, put the 37s back on, and listed the set of 40s for sale. 37s have been hard enough on the Jeep. My fourth locker is not functioning right, I have been through two sets of 5.13 gears, one set of rear axle shafts, put RCV axles in the front, replaced the ball joints, and all the front steering components. Yet I am not done. I will be ordering a Fusion 4x4 60 for the back in about two months. I have found that the Dana 44 will not hold up to the amount and type of wheeling that I do even with 37s.


Just the price of wheeling. If I was on 40s, I would also be dealing with a 20% loss of mileage too. The loss of mpg is a big deal out west. I pull a camper all over the US and there are places out west that I would not have enough fuel to get from one gas station to the next gas station. Pulling my camper with 40s, the best I would see is 8 mpg.

Towing the Jeep behind my ram rebel from here to CO and back we averaged 8mpg…I’ve yet to find this mythical location out west that gas is more than 150 miles away from the last station though? Sure some stretches out in the desert are 70-90 miles between stations, but unless you’re getting less than 5mpg I still argue you can get anywhere comfortably. If the OP is going to run a light 40 like a bfg or milestar vs the heavy nitto 37’s he currently runs, I doubt he’ll see more than a 10% drop in fuel economy anyway. 12-13mpg still gives an effective range of 240-260 miles which is more than enough to get anywhere in this country. The Mojave road is one of the longest trails I’ve ever seen and it’s only 100 miles from end to end, not to mention there are at least 3 locations along it where you only need venture a few miles off course to a fuel station. You could likely run the entire thing with a 5 gallon tank getting 5mpg if you stopped at every available station. On 38’s we averaged 15mpg. Fueled up in Merced, drove 100 miles up a mountain from 100’ elevation to 10k’, not realizing the fuel stations in shaver lake were not 24hrs. Ran the entire Dusy Erishim trail 40 miles in 4LO, and still made it the 30 miles back to town. Fuel issues in a vehicle with a 20 gallon tank that gets even high single digit mpgs are a myth. Would it be nice to go 400 miles between fill ups? Absolutely, but it’s far from necessary. I haven’t run 40’s on a JL, but even on 38x13.50’s running all those trails you mentioned, our experience has been much more durable than what you described. The stock ball joints lasted 35k miles. Still had stock axle shafts, rear drive shaft, rear track bar and tie rod at 62k miles. Front driveshaft needed replaced after flexing it out too many times on 29” long front shocks. I’m not saying 40’s are perfect on stock axles, but we’ve all seen people running 40’s without major upgrades or issues on this forum just as we’ve seen people destroy their axles on stock tires. The idea that there’s some magic leap from 37/38’s to 40’s ignores all other factors from weight to driving style. Odds are 39’s will be our next tire choice on the XR, and I’ll be sure to keep everyone updated on failures and/or success.

 

[wibornz]

The JL shows the Jeep empty at 17 gallons. Yes I am aware the tank is 21 gallons before it stops running. Done that. 8 mpg in a relatively flat Michigan towing a camper. Running HYW 50 across norther Utah and Nevada there are places that 168 miles may not be enough. I think I counted 11 or 12 mountain passes from Moab to Reno. I would not be getting 8 mpg pulling the camper over mountain passes. I could easily be down around 5 mpg. There are places in California where gas can be 150 miles between stations also.

For those not familiar with the high desert between Oregon and Nevada there is a stretch between Lakeview, OR and Winnemucca, NV that has a hot, grueling 211 miles without fuel.

Also there are places where you don’t necessarily know that fuel is available because it might be 5 to 10 miles out of your way to get the fuel, so you don’t stop and you pull in to a gas station and take 20.4 gallons of fuel with the next fuel stop 78 miles away.

This also means you can not wheel or explore at all between these stretches because of the lack of fuel. An extra 5 gallons of fuel mean 40 more miles at 8 mpg.

Just because you don’t think these places don’t exist, does not mean you are correct.

Then of course any of these places you could easily have heavy head winds that can drastically impact mileage.

 

[wibornz]

Sure there are people that carefully wheel 40s. This is not the norm. If it was the norm, nobody would be spend $20,000 on 1 ton axles. Nobody wants to spend $20,000 on axles. They do it out of necessity.

 

[Zandcwhite]

The JL shows the Jeep empty at 17 gallons. Yes I am aware the tank is 21 gallons before it stops running. Done that. 8 mpg in a relatively flat Michigan towing a camper. Running HYW 50 across norther Utah and Nevada there are places that 168 miles may not be enough. I think I counted 11 or 12 mountain passes from Moab to Reno. I would not be getting 8 mpg pulling the camper over mountain passes. I could easily be down around 5 mpg. There are places in California where gas can be 150 miles between stations also.

For those not familiar with the high desert between Oregon and Nevada there is a stretch between Lakeview, OR and Winnemucca, NV that has a hot, grueling 211 miles without fuel.

Also there are places where you don’t necessarily know that fuel is available because it might be 5 to 10 miles out of your way to get the fuel, so you don’t stop and you pull in to a gas station and take 20.4 gallons of fuel with the next fuel stop 78 miles away.

This also means you can not wheel or explore at all between these stretches because of the lack of fuel. An extra 5 gallons of fuel mean 40 more miles at 8 mpg.

Just because you don’t think these places don’t exist, does not mean you are correct.

Then of course any of these places you could easily have heavy head winds that can drastically impact mileage.

Lakeview to Winnemucca has gas in the middle of that 211 miles though, 85 miles from the Nevada side or 125 miles from the Oregon side. Of course you can plan routes that avoid gas stations and go hundreds of miles without passing one, but if you're towing heavy into a high enough head wind to drop fuel economy down to 5mpg (I've never seen worse than 12 out of a tank on 38's at 90mph into a high headwind but I don't tow with the jeep) you should probably be planning for fuel stops not avoiding them. Not to mention with a trailer I'd probably throw 10 gallons of spare fuel on there for safe measure. Sure climbing a steep grade you might hit 5mpg, but odds are you'll be descending those same elevations between passes and averaging closer to 20mpg on the downhills even towing a trailer?

 

[jbcrane]

For those not familiar with the high desert between Oregon and Nevada there is a stretch between Lakeview, OR and Winnemucca, NV that has a hot, grueling 211 miles without fuel.

Also there are places where you don’t necessarily know that fuel is available because it might be 5 to 10 miles out of your way to get the fuel, so you don’t stop and you pull in to a gas station and take 20.4 gallons of fuel with the next fuel stop 78 miles away.

This also means you can not wheel or explore at all between these stretches because of the lack of fuel.

Just because you don’t think these places don’t exist, does not mean you are correct.

Then of course any of these places you could easily have heavy head winds that can drastically impact mileage.

This is so true-well said. I hear others state how little they care about fuel economy driving their Jeep. To me it’s all about balancing range (fuel economy/mpg figures directly into range) with capability for your use case. There’s no one size fits all, rather weighing (literally) benefit vs. range penalty. Out West there’s just more open space between places-which is the draw, isn’t it?

 

[wibornz]

Lakeview to Winnemucca has gas in the middle of that 211 miles though, 85 miles from the Nevada side or 125 miles from the Oregon side. Of course you can plan routes that avoid gas stations and go hundreds of miles without passing one, but if you're towing heavy into a high enough head wind to drop fuel economy down to 5mpg (I've never seen worse than 12 out of a tank on 38's at 90mph into a high headwind but I don't tow with the jeep) you should probably be planning for fuel stops not avoiding them. Not to mention with a trailer I'd probably throw 10 gallons of spare fuel on there for safe measure. Sure climbing a steep grade you might hit 5mpg, but odds are you'll be descending those same elevations between passes and averaging closer to 20mpg on the downhills even towing a trailer?

I am under the impression the fuel stop is no longer in operation that you show. How far out of the way is the Fields station?

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