Michigan driving 4.88 or 5.13 in my JLUR?

[Detroit]

I have searched the forums about gears but never really found the answers to my needs and what is the best gearing for me. I have called several shops in my area and got mixed answers on weather to go with 4.88 or 5.13 gears.

I have a 21 JLUR with an 8 speed and 3.6 with a steel bumper and winch. Im running the Mopar beadlocks and lift with 37" Cooper STT pro tires. Living in SE Michigan its pretty darn flat. I swap between my JL and a G5 for daily driving. We Off-Road as much as possible. In my 8k miles I have been to Drummond Island 3 times many trips to Off-Road parks and many trips to Northern Michigan trails. My expressway speeds are between 70 and 80mph. I wish I could test drive a JL with a 4.88 and 5.13 gears lol. Whis this being said what gears would best suit me? I want 7th and 8th gear back!

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[Some Random Guy]

I recommend 4.88 over 5.13. Granted, my experience is with a 6-speed, but I’ve borderline gone too far for daily driving. I’m in top gear at 50 mph if flat on my 39’s.
Anecdotally I’ve heard auto drivers out here on 37’s that are embarrassed about their mpg when road tripping to MOAB. They say it isn’t worth it, they would have been fine with lower gears.
I miss the U.P. Enjoy it for those of us that left!

 

[Jeepeto]

I’ve got 37s and 4.56s. With beadlocks, 3.5” lift, Trailrax/rotopax and a load out in the back I feel that I would be best suited going to 5.13s. I used to believe 4.88 would be spot on, but the transmission is quick to downshift a gear or two (3 with elevation) with the 4.56s and I just don’t think 4.88 would be enough to eliminate gear hunting altogether.

FWIW, the 4.56s are usable. 4.88 would probably be very close as well. If you were running a bit less lift, lighter wheels/tires, no storage racks and lighter build out it would probably be perfect.

 

[Detroit]

I recommend 4.88 over 5.13. Granted, my experience is with a 6-speed, but I’ve borderline gone too far for daily driving. I’m in top gear at 50 mph if flat on my 39’s.
Anecdotally I’ve heard auto drivers out here on 37’s that are embarrassed about their mpg when road tripping to MOAB. They say it isn’t worth it, they would have been fine with lower gears.
I miss the U.P. Enjoy it for those of us that left!

At first I was like im going with 4.88s then I was like 5.13s. This is a tough one. My biggest thing is getting my 7th and 8th gear back. Love the U.P. We go many times a year.

 

[JEEP4U]

5.13 would be best.

 

[rlong69]

5.13's just had mine installed. 4.88's would be ok, but 5.13's for 37's is the magic.

 

[mnjeeper]

I'm leaning towards 4.88s personally. MN, similar terrain.

It would be nice to drive a full tank of gas with each to have a bit of a guess what difference that makes. It might make a mild difference in my personal choice.

 

[J0E]

No need to guess or get opinions, https://bt39.com/GearWheelSpeed can show exact ratio's if you want to match stock.

 

[Jmos4]

Hi,

My guess would be go for the 5.13's that way 7th and 8th would be a useful gear.

You should look at a Randy's Ring and Pinion gear calculator and see where it runs now then punch in new tire size and both ratios should give you a good idea on where you will be.

I just ordered a 22 JLUR 6mt 4.88's figure I will be going to 35's might be a little high rpms but 5th and 6th will be useful.

Regards,
Jim

 

[wibornz]

I have put 35,000 miles on my JLUR that is outfitted like yours with 5.13 gears. I can pull 18 to 19 mpg on the hyw. I live in Lansing Michigan area and you can drive my Jeep if you would like. I changed my gears at approximately 19,000 miles. I run Cooper STT PRO tires in 37x12.5R17 on heavy deadlocks.

There is no way I would go to 4.88. I am turning about 2200 RPMs at apron 70 mph. I also tow a camper and wheel all over the US. I think in our area, you would be disappointed with 4.88 gears.

From a recent trip to Drummond Island.

 

[wibornz]

Note, I can see 8th gear all the time and at speeds as low as 40 or so mph.

 

[ColoJLRubi]

5.13 for automatic, 4.88 for manual

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