What if.... I don't?

[ABQJeep1848]

Hey Team,
Time to swap tires. 2021, Sport S, Tow Package, 4.10 gearing, 2.5" RE lift. Have a friend that is swapping his 37's for 40's. 37's (KO2's) are still fresh and shiny. For the sake of argument, If I were to strap the hand me down 37's on mine and NOT regear right now, what are the ramifications/consequences in your mind?
This is a money now money later argument.
Thoughts? and Many Thanks,
JP

Sponsored

 

[bleda2002]

You'll be slower off the line, it will suck going up big hills, you'll lose gas mileage, you'll see 7th and 8th gear less other than that not much. I love my regear, but I drove with out it for a long time and it was fine. I know tons of folks driving on 4.10s and 37s and they're happy as clams.

 

[ABQJeep1848]

You'll be slower off the line, it will suck going up big hills, you'll lose gas mileage, you'll see 7th and 8th gear less other than that not much. I love my regear, but I drove with out it for a long time and it was fine. I know tons of folks driving on 4.10s and 37s and they're happy as clams.

That's kinda what I thought, so Thank You for the quick reply. I can do happy clam for now.

 

[Maximus Gladius]

Accentuate the positive…

you’ll look cool.

 

[Zachanadandy]

I don't agree that it will suck on big hills, even towing a trailer. Outside of 1st gear the regear does nothing that a downshift doesn't. Unless you're driving up a vehicle cliff at 30mph or less it's never going to downshift to 1st gear. Even pulling an 8200lb trailer up grades it maintained 65mph without issue even climbing a grade that gains 4k feet of elevation in 20 miles. It never shifted below 4th. All a regear would have done is had it downshift to 5th instead of 4th. No gain in torque, no extra mechanical advantage.

 

[Reddout99]

I'm running 37s on stock 3.73s. No complaints for my type of driving as a daily driver. Have taken long road trips out to California to visit family without issue
You'll find a lot of discussion on this topic

 

[ABQJeep1848]

Accentuate the positive…

you’ll look cool.

Well said...

 

[Freems]

Accentuate the positive…

you’ll look cool.

90% of everything is good presentation.

 

[bleda2002]

I don't agree that it will suck on big hills, even towing a trailer. Outside of 1st gear the regear does nothing that a downshift doesn't. Unless you're driving up a vehicle cliff at 30mph or less it's never going to downshift to 1st gear. Even pulling an 8200lb trailer up grades it maintained 65mph without issue even climbing a grade that gains 4k feet of elevation in 20 miles. It never shifted below 4th. All a regear would have done is had it downshift to 5th instead of 4th. No gain in torque, no extra mechanical advantage.

I guess I've driven up cliffs by your definition. Towing to TN I was indeed in 3rd and 2nd gear going up big long hills that would have been stuck in first gear screaming. I'm towing a camper though so the wind resistance is real.

The main reason I actually regeared was that I was tired of having to use between 1st and 2nd to get up to the cabin, that's besides the much better off the line torque I got towing.

 

[Glamisfan]

I ran 39” bfg mud terrains for 54,000 miles on stock 4:10 gears on my Rubicon JLUR. I’ve never had any complaints. It did not use 8th gear, but it stayed in seventh just fine on the highway. Never hunting for gears. Plenty of power, stops good. Now I’m on 38 inch Nito’s. The only difference when you go to a bigger tires to me is you won’t use 8th anymore. The difference, leaving a stop sign in first gear was maybe a little noticeable at first, but not noticeable at all anymore.

Go for the 37’s. Your jeep will look better and it’ll work better off-road.

 

[Thunderspud]

I have the manual with 4.10s, so maybe not the best comparison.....but recently found a great deal on 37's and temporarily mounted them in place of the 35's I normally run.

Other than the obvious difference in road noise from these mud terrains vs the normal all terrains, I'd be lying if I said I could even tell the difference in normal driving.

I didn't even buy these tires for this truck, but I am now slowly talking myself into leaving them installed.

Maybe just for the season? Eh, who am I kidding......

 

[Zachanadandy]

I guess I've driven up cliffs by your definition. Towing to TN I was indeed in 3rd and 2nd gear going up big long hills that would have been stuck in first gear screaming. I'm towing a camper though so the wind resistance is real.

The main reason I actually regeared was that I was tired of having to use between 1st and 2nd to get up to the cabin, that's besides the much better off the line torque I got towing.

I didn't choose 30mph or less at random. Even with 37s and stock 4.10s you'd be at redline in 1st gear at any speed above that. No it isn't going to downshift to 1st at 40mph and spin the engine over 7k rpms...ever. it wouldn't even let you do something that dumb even if you tried manually shifting. I've never encountered a situation where the truck won't maintain road speed period. Yes it will run all the way up to 6200 rpm to do it... but that's where the 3.6L makes peak hp. It's not a gearing issue it's a high revving engine that needs rpm to produce power. If you're trying to tow up a mountain at 25mph, odds are you're going to see 1st gear even if you regeared.

 

[Chasm]

I'm running 37s on stock 3.73s. No complaints for my type of driving as a daily driver. Have taken long road trips out to California to visit family without issue
You'll find a lot of discussion on this topic

That makes me feel better too. I was planning some taller tires on my 3.73's when these get worn. I'm only thinking 34-35's though. (no lift)

 

[Reddout99]

Keep in mind that you should recalibrate for correct actual tire size with a programmer. I used Jscan. It allows your computer to readjust shift points for the tranny so it drives like normal as well as calibrates your speedo. Probably does a bunch of "other stuff" as well so your JT drives as optimally as it can.

 

[Chasm]

Keep in mind that you should recalibrate for correct actual tire size with a programmer.

Do you know: Does the tire size calibration keep the same max speed?

Sponsored