Let's talk optimal build for 31" tires

Having decided that I want to run a 31" build for now, this thread makes me feel good
So you didnt need to lift it when you put the 31,s on? I thought they were bottoming out or rubbing a bit when you first put them on without the lift.
 
So you didnt need to lift it when you put the 31,s on? I thought they were bottoming out or rubbing a bit when you first put them on without the lift.
I installed a lift! 2” OME light duty springs. With Rancho shocks.

No way I could run 31” with stock suspension for my use.
check my build thread for before and after photos and measurements if you want
 
I installed a lift! 2” OME light duty springs. With Rancho shocks.

No way I could run 31” with stock suspension for my use.
check my build thread for before and after photos and measurements if you want
Yes I have been following and I think I remember you saying tyres were a bit big without the lift but many say its fine to run 31,s on stock height, what do you think, ok on road but not off road?

cheers
 
I had 31's on the stock suspension for 2-3 months before I put my lift on. I also had aftermarket wheels with 3.75 inches of backspacing, so they stick out a little further. And I had the slightly wider Rubicon flares. I didn't take it off road during that time, but I did have a couple situations where the tires would rub the underside lip of the rear flares on road. I don't know what you call it, but the road had a long stretch of high and low spots. They kind where when you drive over it at speed, the whole vehicle bobs up and down, like going over waves on the water.
 
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I had 31's on the stock suspension for 2-3 months before I put my lift on. I also had aftermarket wheels with 3.75 inches of backspacing, so they stick out a little further. And I had the slightly wider Rubicon flares. I didn't take it off road during that time, but I did have a couple situations where the tires would rub the underside lip of the rear flares on road. I don't know what you call it, but the road had a long stretch of high and low spots. They kind where when you drive over it at speed, the whole vehicle bobs up and down, like going over waves on the water.
Road Dips, purpose built low points sometimes with pipe crossings and headwalls (culverts) in a long stretch of would be flat highway for storm water to fall to the low points so the road doesn't flood.!
 
I had 31's on the stock suspension for 2-3 months before I put my lift on. I also had aftermarket wheels with 3.75 inches of backspacing, so they stick out a little further. And I had the slightly wider Rubicon flares. I didn't take it off road during that time, but I did have a couple situations where the tires would rub the underside lip of the rear flares on road. I don't know what you call it, but the road had a long stretch of high and low spots. They kind where when you drive over it at speed, the whole vehicle bobs up and down, like going over waves on the water.
Diffs are still only 1 inch higher than 29,s both aired down or up the same!
Dont get me wrong when I bought my new boots a few weeks ago I should have ordered and waited for a 31" to be delivered to my tire fitter but I thought 31,s were too big for stock height, My fault for not asking first lol
31’s really are too big for stock suspension. If you cycle the suspension you can see this. To run a 31 on stock suspension you need a 1” BL or 1/2 to 1” of bumpstop.

@Fishtaco
Diff clearance is variable. Put a tire up on a rock/log/etc and the diff clearance increases.
 
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31’s really are too big for stock suspension. If you cycle the suspension you can see this. To run a 31 on stock suspension you need a 1” BL or 1/2 to 1” of bumpstop.

@Fishtaco
Diff clearance is variable. Put a tire up on a rock/log/etc and the diff clearance increases.
My limited off roading is in sand, in fact most of Australia's liveable area is sand and diff height is what is important to me if considering any mods so an inch is well just an inch when you are bogged to the axils. We are not allowed to even walk up Aires rock (now Uluru) these days let alone jeep up it lol
 
My limited off roading is in sand, in fact most of Australia's liveable area is sand and diff height is what is important to me if considering any mods so an inch is well just an inch when you are bogged to the axils. We are not allowed to even walk up Aires rock (now Uluru) these days let alone jeep up it lol
Sand, snow, soft ground you want wide instead of tall. Look at what the Iceland folks do for tires.
 
Overall, performance of the Jeep was noticeably degraded. Acceleration, braking, and handling characteristics were not what they were like on 31" tires. Yes, you can mitigate some of this with gearing and better brakes, but the higher you go up, and the more weight you add, the more you shift the center of gravity.

Also, a big issue has to do with tire width. A 12.5" tire, as part of the 33x12.50 tire, tracks different than a 10.50 tire. Again, this can be partially mitigated with a 33x10.50 tire, but choices in that size are very limited.

To be 100% clear, I'm not saying a 33" tire is bad, it's just different. Different enough that it negatively impacts the daily drivability. Especially, given the majority of jeeps spend 95+% of their time on the road.

Bottom line, a Jeep on 33" tires can be made to drive and handle close to a stock version, or better. However, this takes lots of money and time, which most don't spend in the correct places. In the end, it's a personal choice though, so there's always that!
 
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I had 31's on the stock suspension for 2-3 months before I put my lift on. I also had aftermarket wheels with 3.75 inches of backspacing, so they stick out a little further. And I had the slightly wider Rubicon flares. I didn't take it off road during that time, but I did have a couple situations where the tires would rub the underside lip of the rear flares on road. I don't know what you call it, but the road had a long stretch of high and low spots. They kind where when you drive over it at speed, the whole vehicle bobs up and down, like going over waves on the water.
In my mind the LJ is the exception for 31" tires. I'd run them on a TJ, but the LJ overhang makes them not practical, if you're going to wheel it. If I were doing another LJ, I'd likely do a 33x10.50 build. That way I'd get the extra needed height, but still keep the tire width down.
 
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In my mind the LJ is the exception for 31" tires. I'd run them on a TJ, but the LJ overhang makes them not practical, if you're going to wheel it. If I were doing another LJ, I'd likely do a 33x10.50 build. That way I'd get the extra needed height, but still keep the tire width down.
Arn’t you doing an LJ on 31’s?
 
Arn’t you doing an LJ on 31’s?
TJ
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In my mind the LJ is the exception for 31" tires. I'd run them on a TJ, but the LJ overhang makes them not practical, if you're going to wheel it. If I were doing another LJ, I'd likely do a 33x10.50 build. That way I'd get the extra needed height, but still keep the tire width down.

My TJ is on OME springs and 265/75 16 inch tires, and when I move back to Oregon my Unlimited is going on 33 x 10.5 Kenda Klever RTs on 17 inch JK Moabs.
 
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Yes I have been following and I think I remember you saying tyres were a bit big without the lift but many say its fine to run 31,s on stock height, what do you think, ok on road but not off road?

cheers
IMHO yes. For me, 31" tires with stock suspension was not the right build. I repeat! FOR ME.

It's my daily driver, but my goal is to build it as off road capable as possible within a limited budget, and a very limited product availability.

I ran my TJ roughly for 2 years almost stock. 29" and stock suspension. I decided I wanted to start modifying so the next logical step for me was 31" (I knew from the beginning that I would need the 2" lift).

I am sure (and I've seen) people running 31", 33" and even 35" tires with stock suspension. I believe anyone should build his rig exactly how he wants, and don't care about what others think at all.

BUT... 31", 33" and 35" tires with stock suspension would need a big-huge amount of bump stop extensions. Which means small articulation, not enough up travel. (Check this thread about up travel, if you haven't already. It's Golden : https://wranglertjforum.com/threads/up-travel-whats-the-big-deal.16270/ )

My personal taste is to be off road capable, so I chose some springs that would give me 2"-3". (I got front 3", rear 2.5"), which I think is the right amount of lift to have enough up travel.

If you don't care about off road though, run even 35" tires. Who cares? Just be a little bit careful over bumps etc.

Some photos for examples:
First photo is 31" with stock suspension, second one is 31" with the 2"-3" lift.
You can see clearly I believe how little space there is between tires and the fender flares in the first photo.

IMG_7259.webp
IMG_7301.webp



Just be honest with yourself about how you want to use your TJ, and build it accordingly. There is no right or wrong. Just personal taste. (Well, just don't put big tires without bump stop extensions and no lift, you are going to break it.)
 
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Overall, performance of the Jeep was noticeably degraded. Acceleration, braking, and handling characteristics were not what they were like on 31" tires. Yes, you can mitigate some of this with gearing and better brakes, but the higher you go up, and the more weight you add, the more you shift the center of gravity.

Also, a big issue has to do with tire width. A 12.5" tire, as part of the 33x12.50 tire, tracks different than a 10.50 tire. Again, this can be partially mitigated with a 33x10.50 tire, but choices in that size are very limited.

To be 100% clear, I'm not saying a 33" tire is bad, it's just different. Different enough that it negatively impacts the daily drivability. Especially, given the majority of jeeps spend 95+% of their time on the road.

Bottom line, a Jeep on 33" tires can be made to drive and handle close to a stock version, or better. However, this takes lots of money and time, which most don't spend in the correct places. In the end, it's a personal choice though, so there's always that!

Reason why i ask, is because i am looking at your profile as well as rim in the picture and cant fully figure out if you are on 17" or 15" rim. Not everyone understands that:

On 15", 33s are actually 32.5 , and 31s are somewhere in the 29s area
On 17", 33s are actually 33.1, and 31s are 31.7 (metrics)

15" combo weights less than 17", and 15" 33s are nearly 17" 31s in size.
As far as lift goes, they are almost in need of the same 3" lift. My front is lifted somewhere around 2.7" (a bit higher than 2.5 and just shy of 3 according to the chart), that is splitting hairs to avoid rubbing during the flex on 31.7s

Downsizing from 17" to 15" is next on my list, and going with 33x10.5 should be a straight swap to 31.7 i currently have, seeing your elaboration of your unhappiness with 33s was also beneficial.
Thank you
 
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In my mind the LJ is the exception for 31" tires. I'd run them on a TJ, but the LJ overhang makes them not practical, if you're going to wheel it. If I were doing another LJ, I'd likely do a 33x10.50 build. That way I'd get the extra needed height, but still keep the tire width down.
I'd like to put 33's on, but I don't really want to without re-gearing it. Then that leads to wanting to put a locker (or lockers) at the same time. It's just not in the budget right now, but maybe someday. I don't do any hardcore wheeling, so the 31's with the 2-1/2 spring lift work for me right now. The hardest thing I've done with it is the Dickey Bell hill climb at Uwharrie National forest in NC and I was actually a little surprised the rear bumper didn't drag on anything.
 
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