4.88 Gears Safe For Distance On Highway?

[thedigitalmc]

So I am re-gearing my 2020 Jeep Gladiator, I have 35" tires now and am moving up to 36" or 37" and think I will probobly go with 4.88 Gears.

I see a lot of threads about Gears & Tires & Ratios, but my mechanic cautioned me about taking 4.88 gears on long road trips as thats a lot of RPMs and can wear down the gears quickly and cause failure.

Now I off-road and rock crawl, but it's also my daily driver. Should these gear ratios be saved more for dedeicated off-road vehicles... can I drive 300 miles on the highway to a trail semi-often with 4.88s and not worry about gear failure? Also would 37"s be easier on the gears since it takes longer to rotate 37" tires then a 36"... or is my math way off base lol.

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[TurboChris]

Your mechanic is mis-informed. I would go 37's and you will be perfectly FINE. It will bring you back more in line to how the gear ratios were when it rolled off the line with 32's or 33's. You won't regret it.

 

[thedigitalmc]

Thanks - That is good to know! Makes me feel a bit better.

 

[JerseyMark]

4.88s should be fine on the highway and arguably better for the Jeep if you have large tires like 35s or 37s. The JL Rubicon can be ordered with factory 4.88s and stock 33s. I know because I have a JLUR with this option. It runs fine on the highways. The engine revs a little more, but I actually find that it work well. It doesn’t lug and doesn’t require multiple downshifts frequently. With the pentastar, I would worry more about engine lugging under load than higher rpms particularly with the dual stage oil pump and lower oil pressure at lower rpms.

 

[Panthers65]

Find a new mechanic. The whole point of regearing is to get the RPMs back where they are supposed to be.

Your RPMs dropped when you went to 37's, you need to get them back up (or a bit higher) to get the Jeep driving correctly again.

I put 5.13's in mine, been towing and running interstate ever since with no issues.

 

[Jrgunn5150]

I'd question his competency.

Seems likely he doesn't know wtf he's doing, will screw it up, and blame the rpms, or pokemons, or Lord knows what.

 

[Zachanadandy]

4.88s should be fine on the highway and arguably better for the Jeep if you have large tires like 35s or 37s. The JL Rubicon can be ordered with factory 4.88s and stock 33s. I know because I have a JLUR with this option. It runs fine on the highways. The engine revs a little more, but I actually find that it work well. It doesn’t lug and doesn’t require multiple downshifts frequently. With the pentastar, I would worry more about engine lugging under load than higher rpms particularly with the dual stage oil pump and lower oil pressure at lower rpms.

Lugging under load with an automatic is as misinformed as the mechanic saying 4.88s are too low for driving long distances. It's an 8 speed automatic, it won't lug under load because it will downshift. 4.88s would be great for 37s, I'd hate them with 33s but I drive faster than most. Even the 4 56s with the factory 315s on our xr felt like it could use another gear on the freeway to me, but again the cruise control gets set at 85mph on roadtrips. The 8 speed has such a low 1st gear and 2 overdrives which allow nearly any gearing combo to work. Even from the factory Jeep is all over the map. A JLU sport/Sahara/willys (up until 2024) all came with 32s and 3.45s, which works out to 4.10s and 37s by comparison. The rubicons got 33s and 4.10s, which works out to 4.59s and 37s. The xr's came with 35s and 4.56s, making 4.88s the equivalent ratio for 37s. And now you can order 4.88s and 33s, equal to 5.47s and 37s. The right answer even according to Jeep engineers is run whatever you like for your usage. Having run 5.38s and 38s in our 2019 I can tell you I hated super deep gears and lost 2-3mpg on roadtrips because of it. It was in 8th gear all the time like some want, like any speed over 40mph. For me what's the point of 8 gears if you're through them all by half the speed limit?

 

[1550jrit]

I have 5.38’s and run 37’s. I have run my Jeep for 14 hours straight at 80mph with rpm’s hovering around 2650-2700, I pulled in my driveway and took a temp reading of my diffs following that drive. I can’t recall exactly what the specific temp was, but it was within normal ranges and I could hold my hand to the diff cover with no problem. You’ll be more than fine with 4.88’s, re-gear and don’t look back. Choosing your gear setup is highly personal, so get what makes you feel comfortable. I love my 5.38’s and they work for me, truck feels like a rocket as a daily and serves me well for slow off-road wheeling. I’m also armored up with bumpers, skids and a winch so the deep gears help move all that weight. Good luck!

 

[PuddleJumper]

Lugging under load with an automatic is as misinformed as the mechanic saying 4.88s are too low for driving long distances. It's an 8 speed automatic, it won't lug under load because it will downshift. 4.88s would be great for 37s, I'd hate them with 33s but I drive faster than most. Even the 4 56s with the factory 315s on our xr felt like it could use another gear on the freeway to me, but again the cruise control gets set at 85mph on roadtrips. The 8 speed has such a low 1st gear and 2 overdrives which allow nearly any gearing combo to work. Even from the factory Jeep is all over the map. A JLU sport/Sahara/willys (up until 2024) all came with 32s and 3.45s, which works out to 4.10s and 37s by comparison. The rubicons got 33s and 4.10s, which works out to 4.59s and 37s. The xr's came with 35s and 4.56s, making 4.88s the equivalent ratio for 37s. And now you can order 4.88s and 33s, equal to 5.47s and 37s. The right answer even according to Jeep engineers is run whatever you like for your usage. Having run 5.38s and 38s in our 2019 I can tell you I hated super deep gears and lost 2-3mpg on roadtrips because of it. It was in 8th gear all the time like some want, like any speed over 40mph. For me what's the point of 8 gears if you're through them all by half the speed limit?

agreed, I decide to drop down to 35s to tow because regearing on 37s didn't make sense. Maybe 4.88s but even then thats a lot of money for so little gain.

 

[Badweather]

5.13 gears and 37” tires, I routinely drive long distance and absolutely no issues. Going from 4.1 to 5.13 is a 20% change you will definitely feel the change but it’s not a crazy change. Make sure you have a means to tell your transmission you made a gear change as well as a tire diameter change or your shift points and speedometer will be incorrect.

 

[RangerG]

So I am re-gearing my 2020 Jeep Gladiator, I have 35" tires now and am moving up to 36" or 37" and think I will probobly go with 4.88 Gears.

I see a lot of threads about Gears & Tires & Ratios, but my mechanic cautioned me about taking 4.88 gears on long road trips as thats a lot of RPMs and can wear down the gears quickly and cause failure.

Now I off-road and rock crawl, but it's also my daily driver. Should these gear ratios be saved more for dedeicated off-road vehicles... can I drive 300 miles on the highway to a trail semi-often with 4.88s and not worry about gear failure? Also would 37"s be easier on the gears since it takes longer to rotate 37" tires then a 36"... or is my math way off base lol.

I ran 4.88 gears on my JT from San Diego to Grand Canyon to monument Valley and back. No problems.

 

[PuddleJumper]

5.13 gears and 37” tires, I routinely drive long distance and absolutely no issues. Going from 4.1 to 5.13 is a 20% change you will definitely feel the change but it’s not a crazy change. Make sure you have a means to tell your transmission you made a gear change as well as a tire diameter change or your shift points and speedometer will be incorrect.

did gain or lose mpg with the regear. assuming you ran 37s on stock 4.10s for a bit

 

[Badweather]

I loss mpg on the highway I average 15.8 - 16.0 and on the stock 33” tires I was around 16.8 - 17.8. Not a huge difference but something

 

[thedigitalmc]

Wow thanks everyone! All this makes me think running 5.13 might not be a bad idea. I have a full steel exo-cage (not pictured) and loaded down bed (~ 600lbs in the bed at all times usually). I was worried I was getting a bit too low, but it seems like no one is having isues with the gears atthis size at distance.

@Zachanadandy - Based on what you were saying though if I can get away with 4.88s it might work out better in the long run as the deep gears might not be worth it unless it's really nessisary. I don't tow, just have a ton of overlanding gear and roll cage.

 

[Zachanadandy]

Wow thanks everyone! All this makes me think running 5.13 might not be a bad idea. I have a full steel exo-cage (not pictured) and loaded down bed (~ 600lbs in the bed at all times usually). I was worried I was getting a bit too low, but it seems like no one is having isues with the gears atthis size at distance.

@Zachanadandy - Based on what you were saying though if I can get away with 4.88s it might work out better in the long run as the deep gears might not be worth it unless it's really nessisary. I don't tow, just have a ton of overlanding gear and roll cage.

I'd stick to 4.88s for 37s.

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