What do I need to up grades for run 37's tires to JKU Sport 2018.

fatal.d

New member
Hi there. I'm Jeeper from Japan.
My JKU Sport 2018 is still stock almost.
I'm planning to install 37's tires and I've been searching alot to what do I need to up grades run for 37's tire. But I'm extremely worrying about it's dangerous to run 37's with stock front axles Dana 30. I can't up grade it because of my budget. So, is it better to I choice to run 35's? Is anybody here run 37's with stock JKU sport axles?
Please help and give me good advice.
Thank you.


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Jkratt

Member
You will get all sorts of advise. I have a 2015 JKU sport and ran 35's with 3.73 gears until the tires wore out. I used a simple budget boost at that time. During that time I saved for the 37's and Dynatrac Trail Leader package and new 3 1/2 inch lift to accommodate those 37's. Either way you will want to address brakes, I used the Dynatrac big brake kit and has made the difference between stopping as opposed to rear ended the car in front of me.

You will hear people have run 37's on a Dana 30 with no issues. The biggest hill for those jeeps are the speed bumps at the mall.

There is a lot that goes into bigger tires. Gears, lift size, actual tire size, brakes, suspension parts. It adds up very quickly. Read the posts on lifts and what others have done on this site. Had I done that first, I would have been on 37's along time ago.

Most of us have done this type of upgrade many times on our jeeps until we get it where we think we want it. It seems like 37's are the new 35's and 40's are they new 37's. I will never go 40's without a divorce. It's just way too much.

Bottom line,
35 max for Dana 30
2.5 inch lift, spring or budget boost
Address the brakes
Maybe gears if you have 3.21
Locker for the rear

Enjoy the shit out of it and fiqure out what you need vs what you want.
 

fatal.d

New member
You will get all sorts of advise. I have a 2015 JKU sport and ran 35's with 3.73 gears until the tires wore out. I used a simple budget boost at that time. During that time I saved for the 37's and Dynatrac Trail Leader package and new 3 1/2 inch lift to accommodate those 37's. Either way you will want to address brakes, I used the Dynatrac big brake kit and has made the difference between stopping as opposed to rear ended the car in front of me.

You will hear people have run 37's on a Dana 30 with no issues. The biggest hill for those jeeps are the speed bumps at the mall.

There is a lot that goes into bigger tires. Gears, lift size, actual tire size, brakes, suspension parts. It adds up very quickly. Read the posts on lifts and what others have done on this site. Had I done that first, I would have been on 37's along time ago.

Most of us have done this type of upgrade many times on our jeeps until we get it where we think we want it. It seems like 37's are the new 35's and 40's are they new 37's. I will never go 40's without a divorce. It's just way too much.

Bottom line,
35 max for Dana 30
2.5 inch lift, spring or budget boost
Address the brakes
Maybe gears if you have 3.21
Locker for the rear

Enjoy the shit out of it and fiqure out what you need vs what you want.

Thank you for advices. I've asked to some Jeepers who already have 37's and Pro shops. Most of people said that its no problem run 37's at onroad and light offroad with Dana 30 and I knew I need many correction parts with nice coils and shocks.

And some people who give up 37's and chosen 35's said I should better to chosen 37's. Of course I know everybody have budget problem. That's the big point.

I try and may be clear budget problem so I'm gonna build 37's JKU.




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I personally won't run anything over 35s on a D30. It's just not worth the risk to me, personally, since this is my DD and I have to drive it home from wherever I'm wheeling.

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ssh6314

Member
This is going to depend on so many factors, what you use your Jeep for, how hard you use your Jeep, can you afford to fix it when something potentially serious breaks. These are all things you have to know, the path to 37s isn't a cheap one if you do it right. I just made the jump to 37s myself.

Your going to need:

Tires.
Rims with enough backspacing or spacers
A 3.5 inch lift that addresses your front and rear track bars, front lower control arms, sway bar links, shocks. Preferably with new adjustable parts.
Big brake kit (your stock brakes will be dangerous at best, and straight useless in emergency braking)
Trimmed or flat fenders
Re-gear (4.88 in a D30)
Inner C gussets. (Not mandatory, but I wouldn't go without them personally, Evo makes a nice kit)
Alignment and axle geometry adjustment.

Personally I wouldn't go over 35s with a sport. The potential headaches and costs of 37s on a D30, the odds are not in your favor.

A potential route to 37s that is on the cheaper end is to find someone selling a there Rubicon axles, these are by no means a Prorock 44 but you'll have a little more peace of mind.
 
Lots of good advice above. I ran 35’s and stock gearing on my 2014 JKU sport for about a year with a 2.5” lift and some steering upgrades. Found that it handled most of what I was willing to play on just fine. However I bought a sport with the intention of building it up so I knew Axles, brakes suspension shocks etc were in the future so I saved and did it right the first time. It’s easy to spend your money many times over chasing a build but in the long run, you’ll be better off with making a very clear plan on what you want and then saving to do it right the first time.

I’m currently running a complete front axle upgrade, Dynatrac brake upgrade. Upgraded Drag link, Tie rod and track bar and lower control arms. Wheels with the proper backspacing and roughly 3.75-4” or lift (not really sure because it’s a mix and match of parts that I used to get everything just where I wanted it. Shocks fenders etc. gears and lockers and 37x13.50 coopers. It can add up fast so you really need to have a clear plan of what you want and need out of your Jeep.
 
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