2012 JK Automatic & Axle on 35 or 37 tires? - JKowners.com : Jeep Wrangler JK Forum
 
LinkBack Thread Tools Display Modes
post #1 of 23 Old 02-01-2014, 07:59 PM Thread Starter
Newbie
 
Join Date: Feb 2014
Location: Puerto Rico
Age: 47
Posts: 9
Feedback: 0 reviews
Question 2012 JK Automatic & Axle on 35 or 37 tires?

Hello guys.
I'm waiting for my RK 3.5" X Factor and Bilstein 5100 to install it on my 2012 JK 4 door and I"m thinking to use 35 or 37 tires. As every body know, I need to re gear. My trans is an auto. I drive between 55 and 65 mph on High way for about 30 minutes, on a City may be 30 minutes more and about 30 to 45 minutes on hills. Two times a day. (90% on road and 10% off road, Mud and Rock Climb).

Based on your knowledge guys, 4:88 or 5:13?

I"m going to appreciate all your support.

Last edited by Kelvin1971; 02-01-2014 at 08:22 PM.
Kelvin1971 is offline  
Sponsored Links
Advertisement
 
post #2 of 23 Old 02-01-2014, 08:35 PM
Granite Guru
 
Join Date: Feb 2013
Location: SoCal IE
Age: 52
Posts: 271
Feedback: 0 reviews

Welcome, if your jeep is a rubicon I would do 513 and 35" tires. I had this combo and it worked great. I now have 538 and 37" tires along with the necessary axel upgrades to keep the breakage to a minimum. If you plan on a lot of wheeling 37" tires will tax the stock components. When you have the axel out it may be a good idea to buy a set of upgraded knuckles and ball joints.
Doormandan is offline  
post #3 of 23 Old 02-01-2014, 09:29 PM
Rock God
 
UnlimiDozer's Avatar
 
Join Date: Mar 2012
Location: Tulare, CA
Posts: 1,494
Garage
Feedback: 0 reviews

Mine (2012 Unlimited Rubicon auto) is on 37" MTR/Ks with stock axles other than the 5.13s. Lots of JKs out there running 37s on stock axles. Upgrade when you can; you don't have to do it right away. I'd go 4.88s with 35s and 5.13s with 37s. 37s and 5.13s will already run your RPMs a little higher than factory 4.10s and Rubi tires. Save the 5.38s for the 40s, but then you need to give some serious attention to your axles.

My Build Thread:
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.


I'm the NRA
JOIN HERE:
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
UnlimiDozer is offline  
Sponsored Links
Advertisement
 
post #4 of 23 Old 02-02-2014, 06:51 AM Thread Starter
Newbie
 
Join Date: Feb 2014
Location: Puerto Rico
Age: 47
Posts: 9
Feedback: 0 reviews

Thanks Guys,
My JK isn't a Rubi. Dana 30 front and Dana 44 rear.

Makes any difference?

Best Regards.

Last edited by Kelvin1971; 02-02-2014 at 07:04 AM.
Kelvin1971 is offline  
post #5 of 23 Old 02-02-2014, 07:30 AM
Wheeler
 
Join Date: Jan 2014
Location: Alpine CA
Age: 43
Posts: 18
Feedback: 0 reviews

I have a 2012 unlimited rubi 4" Currie lift on 37s with 4.88 gears. It nice cause your not revving to high going down the freeway. At 70mph Im around 2600rpm, where if you had 5.13s you would probably over 3000rpm. I can maintain 70 mph on freeway even through mountains no problem.
1nuthead is offline  
post #6 of 23 Old 02-02-2014, 07:57 AM Thread Starter
Newbie
 
Join Date: Feb 2014
Location: Puerto Rico
Age: 47
Posts: 9
Feedback: 0 reviews

How is the fuel impact on 4:88 on 35s and 37s.
More or less efficiency than stock?

Last edited by Kelvin1971; 02-02-2014 at 08:20 AM.
Kelvin1971 is offline  
post #7 of 23 Old 02-03-2014, 06:23 AM
Granite Guru
 
ratchettt's Avatar
 
Join Date: Apr 2013
Location: Tennessee
Posts: 351
Feedback: 0 reviews

Quote:
Originally Posted by UnlimiDozer View Post
. I'd go 4.88s with 35s and 5.13s with 37s.
Agree

2013 JKR, Auto, Yukon 4.56, Goodyear MTR/K 35/12.5/17 on XD222 KMC Enduro Beadlocks,Teraflex Big Brakes & Spare Carrier, Warn RC Winch, Metalcloak Front & Rear Bumpers, Metalcloak Overliner Flares & Front Inner Fenders w/ Corner Guards/Tail Lamps, Metalcloak Game Changer 2.5" w/6-Pac's, ARB Diff Covers & Onboard Air, AFE High Tuck Muffler, Front Lower Control Arm Skids, Artec Aluminum Skid System, Poison Spyder Hood Vents, Ripp SC.

There are no winners here; just beguiled participants
ratchettt is offline  
post #8 of 23 Old 02-04-2014, 04:51 AM Thread Starter
Newbie
 
Join Date: Feb 2014
Location: Puerto Rico
Age: 47
Posts: 9
Feedback: 0 reviews

I think 4:88 is the best for my driving conditions.

Thanks for your support guys.

Best Regards.
Kelvin1971 is offline  
post #9 of 23 Old 02-04-2014, 09:04 AM
Trail Concepts Hmfic
 
jdemonto's Avatar
 
Join Date: Oct 2007
Location: Phoenix,Az
Age: 43
Posts: 6,148
Garage
Feedback: 0 reviews

The best gearing for 35's are 4.10's on a 3.6 Jeep. We build Rubicons with 37's and 4.10's and you lose a bit of 5th gear in the hills. I think 4.88's will kill your hwy mpg.

Jason

Jeep Sales/Jeep JK Conversions/Parts
602-314-5356 or
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.


To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
/
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
/
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.

Rock Krawler American Expedition Vehicles Poly Performance Spod RCV Performance Dynatrac Poison Spyder Magnuson Superchargers Rock Monster Wheels Surprise Straps
jdemonto is offline  
post #10 of 23 Old 02-04-2014, 12:02 PM Thread Starter
Newbie
 
Join Date: Feb 2014
Location: Puerto Rico
Age: 47
Posts: 9
Feedback: 0 reviews

Hi Jason,
In between is 4:56, or not?

Regards.
Kelvin1971 is offline  
post #11 of 23 Old 02-04-2014, 01:24 PM
Granite Guru
 
ratchettt's Avatar
 
Join Date: Apr 2013
Location: Tennessee
Posts: 351
Feedback: 0 reviews

Quote:
Originally Posted by jdemonto View Post
The best gearing for 35's are 4.10's on a 3.6 Jeep. We build Rubicons with 37's and 4.10's and you lose a bit of 5th gear in the hills. I think 4.88's will kill your hwy mpg.

Jason
Quote:
Originally Posted by Kelvin1971 View Post
Hi Jason,
In between is 4:56, or not?

Regards.
This is why there is chocolate and vanilla.

I would have recommended 4.56 to you but your choice was 4.88 or 5.13 in the OP. I was torn between 4.56 and 4.88 like you are torn between 4.88 and 5.13. I had 4.10's with the new 35's and couldn't live with it. I would still like to try my 35's with 4.88's to compare. Having said this I think the likelihood of me wishing I had NOT geared to 4.88 was the greater risk. I am happy because the 4.10 and stock tire performance is back with the new 4.56 and 35's. Many believe the difference between 4.10 and 4.56 is not worth the cost. I disagree.

Good luck.

-Joe

2013 JKR, Auto, Yukon 4.56, Goodyear MTR/K 35/12.5/17 on XD222 KMC Enduro Beadlocks,Teraflex Big Brakes & Spare Carrier, Warn RC Winch, Metalcloak Front & Rear Bumpers, Metalcloak Overliner Flares & Front Inner Fenders w/ Corner Guards/Tail Lamps, Metalcloak Game Changer 2.5" w/6-Pac's, ARB Diff Covers & Onboard Air, AFE High Tuck Muffler, Front Lower Control Arm Skids, Artec Aluminum Skid System, Poison Spyder Hood Vents, Ripp SC.

There are no winners here; just beguiled participants
ratchettt is offline  
post #12 of 23 Old 02-04-2014, 01:37 PM
Granite Guru
 
ratchettt's Avatar
 
Join Date: Apr 2013
Location: Tennessee
Posts: 351
Feedback: 0 reviews

P.S.

My old mileage was 17-18 town 20-21 highway. Now 12-14 town and 17-18 town. With 4.88 I wonder what these numbers might be.

2013 JKR, Auto, Yukon 4.56, Goodyear MTR/K 35/12.5/17 on XD222 KMC Enduro Beadlocks,Teraflex Big Brakes & Spare Carrier, Warn RC Winch, Metalcloak Front & Rear Bumpers, Metalcloak Overliner Flares & Front Inner Fenders w/ Corner Guards/Tail Lamps, Metalcloak Game Changer 2.5" w/6-Pac's, ARB Diff Covers & Onboard Air, AFE High Tuck Muffler, Front Lower Control Arm Skids, Artec Aluminum Skid System, Poison Spyder Hood Vents, Ripp SC.

There are no winners here; just beguiled participants
ratchettt is offline  
post #13 of 23 Old 02-04-2014, 01:59 PM
Wheeler
 
JKTHOMPS's Avatar
 
Join Date: May 2012
Location: CA
Age: 38
Posts: 78
Feedback: 0 reviews

Quote:
Originally Posted by Kelvin1971 View Post
Hello guys.
I'm waiting for my RK 3.5" X Factor and Bilstein 5100 to install it on my 2012 JK 4 door and I"m thinking to use 35 or 37 tires. As every body know, I need to re gear. My trans is an auto. I drive between 55 and 65 mph on High way for about 30 minutes, on a City may be 30 minutes more and about 30 to 45 minutes on hills. Two times a day. (90% on road and 10% off road, Mud and Rock Climb).

Based on your knowledge guys, 4:88 or 5:13?

I"m going to appreciate all your support.
I always go back to the "if I knew then what I know now" I probably would have done things differently, but I knew I was going to modify everything on my Jeep, so maybe someone else will find this helpful.

I agree... on the 2012+ auto the 4.88s are ideal for 37s (4.56 for 35s)... but that is on the auto. On the manual I would say 4.88 or 5.13s would be ideal for 37s.

One more thing to consider when regearing is your final crawl ratio, and since you indicate you are not really a rock crawler and do mainly trails and mud, you don't really have to consider the below, but just in case you find it helpful.

Your crawl ratio is easy to figure out, and ideally your final drive or crawl ratio should at least be between 50 to 1 (50:1) and 70 to 1 (70:1) for rock crawling performance.

Transmission First Gear Ratio x Transfer Case Low Range Ratio x Axle Ratio = Final Crawl Ratio

For example, a stock wrangler Sport is 3.59 x 2.72 x 3.21 = 31.35
With 4.88s: 3.59 x 2.72 x 4.88 = 47.65
with 5.13 (which I cannot confirm if this can be done on a D30): 3.59 x 2.72 x 5.13 = 50.09

Now a 2012 Rubicon Auto Stock 3.59 x 4.1 x 4.1 = 60.35
Rubi with 4.88s: 3.59 x 4.1 x 4.88 = 71.83
Rubi with 5.13s: 3.59 x 4.1 x 5.13 = 75.51

The 2012 Manual Rubi’s first gear ratio is 4.46... so right out of the box you are: Stock: 4.46 x 4.1 x 4.1 = 74.97...
With 4.88s: 4.46 x 4.1 x 4.88 = 89.24
With 5.13: 4.46 x 4.1 x 5.13 = 93.81

Just to put the auto and manuals into prospective. You can see that right out the box the rubi's tc 4:1 ratio makes a huge difference for crawling.

However, the crawl ratio is obviously for when you are in 4wd. For two wheel drive operation and daily driving, you don’t have to worry about the crawl ratio, but you do need to worry about rotating the tires with less stress on the tranny. As someone mentioned, the 5.13s would give you your pep back, but running highway speeds your RPMs would be higher than stock. I personally would recommend 4.88s or 5.13s with 37s on the 2012+ manual and 4.88s on the auto for 37s and 4.56 for 35s.

Don't forget you will need a programmer when you change the gears too (I recommend superchips).

I hope this helps… basically you can’t go wrong with 4.88s with 37s and 4.56 with 35s and the 2012+ jeeps with autos.
JKTHOMPS is offline  
post #14 of 23 Old 02-04-2014, 03:06 PM
Granite Guru
 
ratchettt's Avatar
 
Join Date: Apr 2013
Location: Tennessee
Posts: 351
Feedback: 0 reviews

JLTHOMPS,

Excellent!

I'm no engineer. I calculated my crawl ratio to be 67(I can do arithmetic). Obviously tire size will affect the leverage of our Jeeps' tires at any given ratio. I'm not able to do the physics, but can you introduce tire size into your formula to index different torque pounds(is that a term?) of thrust at tire-meets-terrain?

Trying to make sense.

2013 JKR, Auto, Yukon 4.56, Goodyear MTR/K 35/12.5/17 on XD222 KMC Enduro Beadlocks,Teraflex Big Brakes & Spare Carrier, Warn RC Winch, Metalcloak Front & Rear Bumpers, Metalcloak Overliner Flares & Front Inner Fenders w/ Corner Guards/Tail Lamps, Metalcloak Game Changer 2.5" w/6-Pac's, ARB Diff Covers & Onboard Air, AFE High Tuck Muffler, Front Lower Control Arm Skids, Artec Aluminum Skid System, Poison Spyder Hood Vents, Ripp SC.

There are no winners here; just beguiled participants
ratchettt is offline  
post #15 of 23 Old 02-05-2014, 04:56 AM Thread Starter
Newbie
 
Join Date: Feb 2014
Location: Puerto Rico
Age: 47
Posts: 9
Feedback: 0 reviews

Hello guys, all of you are the best.

I'm very clear now. I decide 4:88 and 37s.
37s tires look better in my opinion.
Thanks to all of you for all your support.

About superchips.... I see superchips online for $149. I ask on different local shops for re-program and they charge $300 or more for re-program.

Any reason that I need go to the shop "experts"?
I can buy the superchips and as I read is not a rocket science to program.

Best Regards.
Kelvin1971 is offline  
post #16 of 23 Old 02-05-2014, 05:23 AM
JKowners Vendor
 
KrawlOff-Road.com's Avatar
 
Join Date: Oct 2010
Location: SC
Posts: 2,324
Feedback: 37 reviews

Good choice!

With your JK being a 2012, I say go either 4.56 or 4.88. 4.88 will give you a bit more room to play with. We run 40's on our 2013 and run 5.13's. It would be way to much for your 37's.

What gearing do you have now?

Here is our gear packages. We always recommend doing the master install kit as well.
http://www.krawloff-road.com/product_p/gearmaster.htm

And on the Superchips, the FlashCal is the one for around $150. The one around $300 is the FlashPaq. It does a lot more. Most guys see that the options on the FlashCal is more than enough for what they are wanting to do. We have ran both of them and they work good. The FlasPaq just goes more in depth in the tunning....
http://www.krawloff-road.com/product_p/sci3570.htm

If there is anything we can do to help, just let us know!

-Jason


To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
:

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
Phone: 864-437-8029
KrawlOff-Road.com is offline  
post #17 of 23 Old 02-05-2014, 05:29 AM
Granite Guru
 
ratchettt's Avatar
 
Join Date: Apr 2013
Location: Tennessee
Posts: 351
Feedback: 0 reviews

Quote:
Originally Posted by Kelvin1971 View Post

Any reason that I need go to the shop "experts"?
I can buy the superchips and as I read is not a rocket science to program.

Best Regards.
Good choice on gears if you want 37's IMO. No need to go to a shop with FlashCal or FlashPac. You can handle.

2013 JKR, Auto, Yukon 4.56, Goodyear MTR/K 35/12.5/17 on XD222 KMC Enduro Beadlocks,Teraflex Big Brakes & Spare Carrier, Warn RC Winch, Metalcloak Front & Rear Bumpers, Metalcloak Overliner Flares & Front Inner Fenders w/ Corner Guards/Tail Lamps, Metalcloak Game Changer 2.5" w/6-Pac's, ARB Diff Covers & Onboard Air, AFE High Tuck Muffler, Front Lower Control Arm Skids, Artec Aluminum Skid System, Poison Spyder Hood Vents, Ripp SC.

There are no winners here; just beguiled participants
ratchettt is offline  
post #18 of 23 Old 02-05-2014, 06:32 AM Thread Starter
Newbie
 
Join Date: Feb 2014
Location: Puerto Rico
Age: 47
Posts: 9
Feedback: 0 reviews

Quote:
Originally Posted by KrawlOff-Road.com View Post
Good choice!

With your JK being a 2012, I say go either 4.56 or 4.88. 4.88 will give you a bit more room to play with. We run 40's on our 2013 and run 5.13's. It would be way to much for your 37's.

What gearing do you have now?

Here is our gear packages. We always recommend doing the master install kit as well.
http://www.krawloff-road.com/product_p/gearmaster.htm

And on the Superchips, the FlashCal is the one for around $150. The one around $300 is the FlashPaq. It does a lot more. Most guys see that the options on the FlashCal is more than enough for what they are wanting to do. We have ran both of them and they work good. The FlasPaq just goes more in depth in the tunning....
http://www.krawloff-road.com/product_p/sci3570.htm

If there is anything we can do to help, just let us know!

-Jason
Thanks again people,

Jason,
I think is 3:21. Is a Sport Wrangler Unlimited. Too slow reaction time with 31s. Ofcourse I"m comparing with my Dune Buggy when I was 18. (VW 2000cc Turbo Charged) is not the same. Also my personal daily car is BMW 540I. This is my first Jeep.

I read about you on your page and I'm very happy with your commitment. That is what my girlfriend and me are doing with our sons. her son 16, my son 14. They are real good boys. I hope more people think like us, specially in my Island (Puerto Rico) where we have a lot of criminality.

Best Regards.

Last edited by Kelvin1971; 02-05-2014 at 08:20 AM.
Kelvin1971 is offline  
post #19 of 23 Old 02-05-2014, 06:41 AM
Granite Guru
 
Join Date: Oct 2012
Location: Rockford IL
Age: 39
Posts: 148
Feedback: 0 reviews

For how much you drive, I wouldn't go larger than 35in tires. I have 37's now on a 3.8 auto with 5.13 and I can't wait to move back down to 35's. If it is a dedicated off road jeep, 37's or larger would be good, but for daily driving, it sucks.
neil.cross is offline  
post #20 of 23 Old 02-05-2014, 06:53 AM Thread Starter
Newbie
 
Join Date: Feb 2014
Location: Puerto Rico
Age: 47
Posts: 9
Feedback: 0 reviews

Quote:
Originally Posted by neil.cross View Post
For how much you drive, I wouldn't go larger than 35in tires. I have 37's now on a 3.8 auto with 5.13 and I can't wait to move back down to 35's. If it is a dedicated off road jeep, 37's or larger would be good, but for daily driving, it sucks.
Hello Neil,
Is a daily drive car. I want to try 37s for the look plus I have order all the parts for a nice handle on road. All you can imagine, drag link flip, SS, ect. If doesn't work I go down to 35s. That's why I'm thinking on 4:88, to have a little more room to play.

Best Regards.

Last edited by Kelvin1971; 02-05-2014 at 08:44 AM.
Kelvin1971 is offline  
post #21 of 23 Old 02-09-2014, 05:48 PM
Wheeler
 
JKTHOMPS's Avatar
 
Join Date: May 2012
Location: CA
Age: 38
Posts: 78
Feedback: 0 reviews

Quote:
Originally Posted by ratchettt View Post
JLTHOMPS,

Excellent!

I'm no engineer. I calculated my crawl ratio to be 67(I can do arithmetic). Obviously tire size will affect the leverage of our Jeeps' tires at any given ratio. I'm not able to do the physics, but can you introduce tire size into your formula to index different torque pounds(is that a term?) of thrust at tire-meets-terrain?

Trying to make sense.
Sorry for the delay, I was at King of The Hammers in SoCal all week.

Let me think about this...
JKTHOMPS is offline  
post #22 of 23 Old 02-10-2014, 07:47 AM Thread Starter
Newbie
 
Join Date: Feb 2014
Location: Puerto Rico
Age: 47
Posts: 9
Feedback: 0 reviews

Thanks for your support JKTHOMPS! I"ll appreciate .

Last edited by Kelvin1971; 02-10-2014 at 07:51 AM.
Kelvin1971 is offline  
post #23 of 23 Old 02-11-2014, 07:23 AM
Granite Guru
 
HAFICON's Avatar
 
Join Date: Feb 2012
Age: 35
Posts: 201
Feedback: 0 reviews

Quote:
Originally Posted by jdemonto View Post
The best gearing for 35's are 4.10's on a 3.6 Jeep. We build Rubicons with 37's and 4.10's and you lose a bit of 5th gear in the hills. I think 4.88's will kill your hwy mpg.

Jason
I went this route. 4.88s and 35's highway MPG is 16ish, in town 14ish. But I look good doing it and tons of power. Guess I need some 37s to off set the RPMs.

Last edited by HAFICON; 02-11-2014 at 07:26 AM.
HAFICON is offline  
Sponsored Links
Advertisement
 
Reply

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the JKowners.com : Jeep Wrangler JK Forum forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:
OR

Log-in










Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes
Linear Mode Linear Mode



Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome