37's and 4:10 gears

[Elwoods Rubicon]

Thinking about ordering a Gladiator Mojave or Rubicon. I would like to run 37s and see that many do. I have a 2016 JKUR with 35's and I also have an AEV ProCal to adjust for tire diameter and transmission shifts. It works perfectly for that I do. I have read about the Tazer a little bit, but unsure about what all it is capable of regarding this.

My question is this: I am very unfamiliar with the 8 speed auto. If I were to run 37's, would I lose 8th gear or even 7th? I have read the tazer will adjust the speedometer, but does it adjust shift points in the trans.?

How does it drive with larger diameter tires compared to stock? I understand they physics, just concerned about power or lack of and shifting of the transmission. I would prefer to not regear from the 4:10s if I could keep from it.

Thanks so much!

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[GladiatorCruzen]

I believe the Tazer does account for shift points once you enter in the correct tire size. I just did 37’s and a Tazer with my lift and I have been very surprised at how well the Jeep drives. I was also concerned about power, but honestly there is still plenty available. Decent passing power and overall drivability is good IMO with 4:10 gears and the 8 speed auto. If it was my daily driver and I was doing allot of highway driving, I think a regear would be beneficial. Once you get over 70 mph, it’s likely not to see 8th gear unless you do a regear. Mine frequently sees 7th gear though. Although, if I didn’t know it had 8 speeds, I wouldn’t think twice about it, lol. My gas mileage only went down about 1 mpg too. If you live in an area with large hills and mountains, you may want to regear, but otherwise you’re probably fine sticking with the 4:10’s.

 

[KurtP]

4.88 brings 37’s to stock equivalent gearing on the 8 spd. Youll want 5.13’s so you can get a little mechanical advantage to handle a load and heavier weight of the tire.

 

[MrZappo]

I don't think you will be happy without regearing.

My mojave is stock with 33 inch MT tires and it down shifts on the slightest incline on the highway.

It is workable and tolerable with the 33's.

And I've heard that 35's behave the same although I can't imagine how.

37's would be a bridge too far IMHO.

I'm sure it would drive without damage but I'd have to imagine it would be irritating.

Stock is marginal from my perspective.

 

[DeezJT]

I have 37’s and 4.10 gearing on my JT. It’s acceptable for my needs and i get 7th and 8th overdrive gears on highway speeds. Like any Jeep, all jeeps are different based on mods, weight, and locality.

I prefer the drive compared to stock especially when my Jeep is weighed down as my setup is more comfortable than stock.

get the tires that you want and don’t base it on your current gears as gears are more affordable than getting a new set of tires. As for me, all of my previous jeeps have been regeared... this one, however, I may not regear.

 

[AustinL911]

gears are more affordable than getting a new set of tires.

Where you getting gears done? Every post I've ever seen has them around $2000 for both sets with labor. Tires are $300-350 each, give or take.

 

[DeezJT]

@AustinL911 i had my gears done on a JK for 900otd so I expected the same. however I can’t get that price for the JL/Jt. The lowest one is priced at 1400. Locality also plays a factor. I’m in SoCal

 

[tbaker]

I am running 37 inch tires on my gladiator with 4:10 gears and it drives just fine no problem I used the rough country speedometer recalibration to recalibrate my speedometer and the shift points are great if I don’t watch I will end up with a speeding ticket

 

[MoparToYou]

I am running 37" tires on my Gladiator with 4.10 gears and it drives just fine. No problems at all. No need to recalibrate speedometer or change shift points. I used my Lowrance GPS to see how fast I am really going, and now If I want to maintain the 80 mph speed limit on the interstate, I set the cruise at 72 mph. Done deal, works good. Why spend money where it isn't needed?

 

[Gadgetech]

I'm with @MrZappo, the 4.10s are barely enough for my stock Rubicon with 33" tires IMO. I'm looking at the same decision of tire size, mainly because I'd definitely want larger tires with a lift, and it seems 37s go hand in hand with a 2.5" lift. I'm sure it's 'okay' with the 4.10s but mine barely stays in 8th at 75 mph with the 33" tires. Any slight incline and it's kicking down into 7th.

 

[Elwoods Rubicon]

Thanks so much for the replies. A friend just bought a Rubicon with the auto and I drove it last night. I have to say, the difference between the Gladiator with the 8 speed and my 2016 with the 5 speed auto is night and day. I think it will be fine with 37's and a calibration for what I want to do. Now to make a definite decision about Rubicon or Mojave. LOL

 

[Troybilt]

I am running 37" tires on my Gladiator with 4.10 gears and it drives just fine. No problems at all. No need to recalibrate speedometer or change shift points. I used my Lowrance GPS to see how fast I am really going, and now If I want to maintain the 80 mph speed limit on the interstate, I set the cruise at 72 mph. Done deal, works good. Why spend money where it isn't needed?

If your jeep is under warranty and they can prove in a court that you did not recalibrate and your milage is off you are out of luck. Even if you decide to fight a expensive warranty work your leg to stand on goes out the window.

This is one reason I do not unmarry my Tazer when I take it in for service work.

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