Anyone with 37”+ tires doing long road trips?

[RidinDirty]

Just did a 1000 mile trip with 37" and 4.10. Although it did fine, you could definitely feel the drop in power in hills and gear hunting. I'm getting 5.13s installed next month. I've had stock gearing and 37 for about 5months now and for the day to day not a big deal and you can get along fine.

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[Andrew05LJR]

I agree if you got 3.73 gears you shouldn't even run 35's without a regear, but the 4.10s do great with 35's and my buddies running 37's without much difference in performance as my JT. I'm guessing a JLUR is engineered a little different than the JT

Nope, exact same gearing/engineering. Trust me, 37s with a JL/JT needs 488s. Sure, 373 or 410 is manageable and you're not going to ruin anything, but for those who made the change, they're ecstatic just like I am. Returns everything to stock if not better. My JT used to hold 2nd gear a lot, now Im into 4th quickly and rarely have to downshift on the highway at 75-80 which is where I spend a lot of my time. Also, while I don't care for MPG, my highway mileage went from 13.1 to 17. Thats significant and a bonus for me.

 

[Jaydebe]

I just replied to a regearing thread today talking about this a little bit.

I've been running 37's since 9k and have 25k on the truck now at 7 months old.
And I am using a Tazer

IMO, regearing should be an option "if" a few things.

1) Tire, rim combo: Mine are about 105 lbs combined (Methods 31#, Grabber ATXs 72#)
Some people have 120-130# of wheel, that's a ton of weight.


2) PSI: That said, changing the PSI in the tires to 33 and under helped. 35+ and it sat about 1/2 taller with teh General Grabber AT-x tires.

3) Rig Weight: At 9k with 37's and only a tonneau cover and some molly panels; the truck was more than acceptable for driving, even on the highway.

Even with 2 mountain bikes and a cooler in the bed and travelling 700 miles on the highway, I we usually stayed in 8th and pulled 18-19mpg.

Now, as I have added weight to the rig, 1/2 height rack, RTT and more gear, the extra weight dropped 8 and even 7th on open roads and interstates where driving over 75mph was allowed.

My last trip to Az, we avg. just about 13mpg on the highway, open roads, 80mph speeds and headwinds with all of the gear had us in 6th most of the time.

It was this last trip I decided to either drop to 35s or regear to 4.88s; not sure which to do yet.

Otherwise, the 37s have been amazing; even on my non-lifted JTR. Even off roading on the Broken Arrow trail in Sedona, a few places around East Phoenix, and here in WV.

Hope this helps some.

 

[Jeeperjamie]

Nope, exact same gearing/engineering. Trust me, 37s with a JL/JT needs 488s. Sure, 373 or 410 is manageable and you're not going to ruin anything, but for those who made the change, they're ecstatic just like I am. Returns everything to stock if not better. My JT used to hold 2nd gear a lot, now Im into 4th quickly and rarely have to downshift on the highway at 75-80 which is where I spend a lot of my time. Also, while I don't care for MPG, my highway mileage went from 13.1 to 17. Thats significant and a bonus for me.

You got a Manual I'm guessing and that would probably explain it. My buddies averaging 17.4 on 37's in his Max Tow JT 8spd and he lives in Hickory NC and makes regular trips to boone. That's the mountains. I'm not saying 4.88 isn't better, but He never saw anything under 17 since he put the 37's on. Hell with 3.73 gears in my 2010 JKU I got 13.5mpgs on 37's.

Also for reference while driving his we never held 2nd gear ever. If you got a Manual then maybe a regear is a better option, with a 8spd auto you will be fine. Not saying 4.88 wouldn't be better but it want make a 4mpg difference and then you got to start wondering if it's worth the cost

 

[Renegade]

Nope, exact same gearing/engineering. Trust me, 37s with a JL/JT needs 488s. Sure, 373 or 410 is manageable and you're not going to ruin anything, but for those who made the change, they're ecstatic just like I am. Returns everything to stock if not better. My JT used to hold 2nd gear a lot, now Im into 4th quickly and rarely have to downshift on the highway at 75-80 which is where I spend a lot of my time. Also, while I don't care for MPG, my highway mileage went from 13.1 to 17. Thats significant and a bonus for me.

Regearing is desirable, but not necessarily a "need" with the 8-speed in many cases. If you tow or live at high altitude, sure. For most users, it's acceptable with 37s and 4.10. Turn off that gear indicator on the dash and stop obsessing over what gear your double-overdrive (yes, both 7th and 8th are overdrive gears) 8-speed automatic transmission is in, and enjoy driving your Jeep. What is actually missing once you put on 37s is the original first gear torque. The tranny will make it up beyond that by using one gear lower than it would have otherwise. Yes, you lose a little fuel economy, but I didn't buy mine for the fuel economy.

 

[MadMojave]

I recently did a long trip using 37x13.5x17R. Visited 25 states on-road e off-road, during day, night, deep mud, snow, slippery asphalt, trail rocks, concrete roads, alone roads, crowded roads, old roads, rain, winds like hurricane.... My conclusion about the size of your tire is: It doesn’t matter! In long trips everything is about drivability, adapt yourself for all terrain and weather conditions, know your equipment and enjoy the ride. I’m investing right now in an upgrade of lights and a long range fuel thank that will make more sense to me. My old Diesel Land Rover Defender always make me remember that Gladiators have great axels, good suspensions, enough speed, better clearance, room space and technology to take you anywhere at any conditions.

 

[TravisK13]

I just replied to a regearing thread today talking about this a little bit.

I've been running 37's since 9k and have 25k on the truck now at 7 months old.
And I am using a Tazer

IMO, regearing should be an option "if" a few things.

1) Tire, rim combo: Mine are about 105 lbs combined (Methods 31#, Grabber ATXs 72#)
Some people have 120-130# of wheel, that's a ton of weight.


2) PSI: That said, changing the PSI in the tires to 33 and under helped. 35+ and it sat about 1/2 taller with teh General Grabber AT-x tires.

3) Rig Weight: At 9k with 37's and only a tonneau cover and some molly panels; the truck was more than acceptable for driving, even on the highway.

Even with 2 mountain bikes and a cooler in the bed and travelling 700 miles on the highway, I we usually stayed in 8th and pulled 18-19mpg.

Now, as I have added weight to the rig, 1/2 height rack, RTT and more gear, the extra weight dropped 8 and even 7th on open roads and interstates where driving over 75mph was allowed.

My last trip to Az, we avg. just about 13mpg on the highway, open roads, 80mph speeds and headwinds with all of the gear had us in 6th most of the time.

It was this last trip I decided to either drop to 35s or regear to 4.88s; not sure which to do yet.

Otherwise, the 37s have been amazing; even on my non-lifted JTR. Even off roading on the Broken Arrow trail in Sedona, a few places around East Phoenix, and here in WV.

Hope this helps some.

Why 4.88 and not 5.13? I see people posting both all the time. What factors make one better than than the other?

 

[Andrew05LJR]

You got a Manual I'm guessing and that would probably explain it. My buddies averaging 17.4 on 37's in his Max Tow JT 8spd and he lives in Hickory NC and makes regular trips to boone. That's the mountains. I'm not saying 4.88 isn't better, but He never saw anything under 17 since he put the 37's on. Hell with 3.73 gears in my 2010 JKU I got 13.5mpgs on 37's.

Also for reference while driving his we never held 2nd gear ever. If you got a Manual then maybe a regear is a better option, with a 8spd auto you will be fine. Not saying 4.88 wouldn't be better but it want make a 4mpg difference and then you got to start wondering if it's worth the cost

I have an auto. But I also drive aggressively. Had a driven like a normal person, I could see 15-17 with stock 373s.

Regearing is desirable, but not necessarily a "need" with the 8-speed in many cases. If you tow or live at high altitude, sure. For most users, it's acceptable with 37s and 4.10. Turn off that gear indicator on the dash and stop obsessing over what gear your double-overdrive (yes, both 7th and 8th are overdrive gears) 8-speed automatic transmission is in, and enjoy driving your Jeep. What is actually missing once you put on 37s is the original first gear torque. The tranny will make it up beyond that by using one gear lower than it would have otherwise. Yes, you lose a little fuel economy, but I didn't buy mine for the fuel economy.

You can live in whatever fairytale you choose but Id like for people who are looking for real advice to know when you go up in tires size, especially to 37+, regearing SHOULD be done. No one has to do anything, thats why there's TJs with 37s, D30/D35 combos and 307s. However, anytime someone asks this question about regearing, Im going to tell them my experience which regearing is a must if you want to return your Jeep back to close to stock as possible.

As far as fuel economy, I didn't buy it for that either. Stock, driving the same way I do now was 17-18 mpg. 37s installed, same trip, same driving habits, 12-13 mpg. 37s and 488s, 16-17 mpg. Its been 3 weeks with consistent results. MPG was NOT my goal for regearing, I still don't care, but this is factual information people need to and should read when they ask these things

 

[Jeeperjamie]

I have an auto. But I also drive aggressively. Had a driven like a normal person, I could see 15-17 with stock 373s.



You can live in whatever fairytale you choose but Id like for people who are looking for real advice to know when you go up in tires size, especially to 37+, regearing SHOULD be done. No one has to do anything, thats why there's TJs with 37s, D30/D35 combos and 307s. However, anytime someone asks this question about regearing, Im going to tell them my experience which regearing is a must if you want to return your Jeep back to close to stock as possible.

As far as fuel economy, I didn't buy it for that either. Stock, driving the same way I do now was 17-18 mpg. 37s installed, same trip, same driving habits, 12-13 mpg. 37s and 488s, 16-17 mpg. Its been 3 weeks with consistent results. MPG was NOT my goal for regearing, I still don't care, but this is factual information people need to and should read when they ask these things

I get it you had 3.73 gears in yours from the beginning, I was under the impression you were starting at 4.10 gears. I also remember your comparison to a JLRU which I know has 4.10 gears but they get less gas mileage than the JTs do with 4.10 gears for some reason, that's not a fair comparison in my opinion. It's been noted many times on here that the JTR gets worse gas mileage than the Max Tow, I'm still not totally sure why that is.

I get what your saying about regearing but what trying to figure out is how are you only getting 17mpgs after regearing it. I'm assuming yours is a overland or sport with 3.73 gears that you regeared to 4.88. I just guessing that's from some serious aggressive driving above 80 a lot of the time.

 

[Jaydebe]

Short Answer: 37s dropped my rpms by about 200 or so, so I'm only really looking to get those back, nothing more. I also do not rock crawl (I live on the East coast), so I'm not worried about that crawl ratio.

Long Answer: Personally, for me it's that I was actually ok/happy with 37s and 4.10s until I added the weight (400lbs permanent)to the JT for travelling. The weight and tire weight and tire size hit are very noticable on the open roads now.

Mind you, I'm a complete noob at this, but I believe that the 4.88 will give me that 225ish rpms I need to reach the next gear.

In fact, I'm pretty sure that moving to the 37s reduced my rpms by maybe 190-200 ish rpms; so the 4.88s won't "overcompensate," I think I remember reading that 37s on a JTR w/auto could really do fine with something between a 4.55& 4.88.

All that said, I'm completely open to anything in the future. At the end of the day, I usually err on the side of caution and least chance for 2nd time mods.

IE: In the future, If I think 35s/37s, it'll be 4.88, If I think 38/40s, it'll be 5.13s

Why 4.88 and not 5.13? I see people posting both all the time. What factors make one better than than the other?

 

[Andrew05LJR]

I get it you had 3.73 gears in yours from the beginning, I was under the impression you were starting at 4.10 gears. I also remember your comparison to a JLRU which I know has 4.10 gears but they get less gas mileage than the JTs do with 4.10 gears for some reason, that's not a fair comparison in my opinion. It's been noted many times on here that the JTR gets worse gas mileage than the Max Tow, I'm still not totally sure why that is.

I get what your saying about regearing but what trying to figure out is how are you only getting 17mpgs after regearing it. I'm assuming yours is a overland or sport with 3.73 gears that you regeared to 4.88. I just guessing that's from some serious aggressive driving above 80 a lot of the time.

Thats correct. Highways in South Florida will frustrate just about anyone. So I do drive aggressively. Theres a good and long reason behind that, wont get into. But, I drive primarily 75-80+ daily and a good amount of heavy throttle use. went from 37s and 373s Sport S to 37s and 488s with those changes in MPG. Was not expected. But, previously held 6th gear a lot at those speeds. Now, Im in 8th with less shifting and less need to use more throttle. RPM doesn't always mean more fuel used, especially if its in its torque band. Now with 488s, it is. Hopefully that makes more sense, guess I could have expanded more

 

[Jocww]

Im hoping my JTRD on 37s with 2in mopar lift will still give me mid 20s on my road trip. home.

 

[Blackjeepjk]

40’s here
4.10 gears, auto, flashcal adjusted
No long trip yet but getting 19.2mpg on interstate
16.4 city
Will be going to 4.88 in very near future.

 

[VolatileA]

40’s here
4.10 gears, auto, flashcal adjusted
No long trip yet but getting 19.2mpg on interstate
16.4 city
Will be going to 4.88 in very near future.

I don't know how everyone is getting such great mpg, I'm running 38s and getting 14mpg in the city mixed with highway and I'm not even punching it. Fake news! lol

 

[Trippin01]

5.13 gears for 37's. 65-70 mph, 14-16 mpg's, running at about 2100 rpm's. I drive to Moab, Ouray, and other trails. What I've noticed on 38's vs. 37's, is the treads aren't quite as aggressive. Keep in mind you are only adding a 1/2" of clearance. I'm dumping my 4.5" lift and going to the 6" lift with a new front drive shaft, due to rubbing the top of my fenders at full flex. Moab was so much easier going from the 4.10 gears to the 5.13's. I have about a 250-275 cruising range on the highway. I need to add that I do have an RTT on, which I'm sure it creates a little more wind resistance. When I drive locally, I'm getting about 10 mpg's, and I live in the rockies

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