Going from 31s to 33s

YonderNorthwest

YonderNorthwest

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Portland Oregon
I've been doing a bit of poking around the forum to learn what I need to do to get my 99 TJ onto 33 inch tires. My current setup is 31 BF KO2s, stock height Bilstein shocks, stock height Moog springs, and an antirock in the front. I take my jeep on a couple of big offroad trips every year. Biggest obstacles I usually contend with are small rock gardens and washed out roads (think max droop on one side, full stuff on the other). Only rubbing I get with this setup are when I crank the wheel to full stop left or right.

I'm thinking about graduating to 33 inch tires once this set wears out. Since I'm on stock suspension with no issues, my theory is that 1" H&R springs and a 1" or 1.25" body lift would leave me with a similarly rub-free suspension with the bigger tires. Reading around the forum I'm finding the general consensus is that the "right way" to fit 33s is with a 4" lift, and to fit 31s is a 2" lift. I'm running 31s with no lift and the suspension/fenders/clearance have not been an issue.

I feel like there is a big difference in cascading costs between a 1" suspension lift and a 3" suspension lift, and I have to keep the medical bills on my 225k mile jeep in mind. Can someone educate me as to what I am missing in this equation?

Thanks
 
Try it and see if it works for your needs. It's all in the bump stops. :unsure: This is 33s with a 2.25" lift and 33s with a 4" lift. A picture's worth 1000 words.
jeep 33s (2017_11_20 00_38_12 UTC).jpg


IMAG0026 (2017_11_20 00_38_12 UTC).JPG
 
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Duck Doctor said:
Tires may fit but how do you plan to address drivability with the stock gear ratio?
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Regearing is a must. I've got 3.73 gears right now. 5th gear is a dog now, and when pulling my M416 trailer I'm downshifting to 3rd gear to maintain speed unless I get the revs up to 3500. I'm considering 4.88 for 33s or 4.56 for 31s. I think that is a bit taller than most would recommend for those size tires, but with the towing I'd like to be a little taller I think.
 
careful starting a regear thread over here lol I've got 4.56 on 33s (5-speed) and its nice but I don't tow anything
 
YonderNorthwest said:
I've read a couple of those. It's the "I wouldn't run 31s without a 2" lift" comments that have me scratching my head.
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I read 2 pages of one of those threads and had the answer you are still scratching your head about.

You're always welcome to try it. Sometimes I think this is better for some people.

I have read responses to my inquiries on here for years, and I didn't always understand what I was reading. I just thought I did. I'm sure it is still that way with some issues. Once you get under the rig and actually start doing things to it you understand.

I could explain shock travel, bumpstops, valving, backspacing, and the rest of it, but what good would it really do? It's already explained in some of those threads.
 
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I have the BDS 2.5" lift and 33x12.5 tires. I used to have 31" ko2s at stock height (probably a lil under due to sagging) and all I needed to fix my rubbing was some spacers.

I have no rubbing now with 33s, but you're right it did take a lot of time and parts to get there. I did it at the same time as my tummy tuck though, so it's hard to remember what was "needed" for what now lol.

Regarding the gearing though, you're probably fine. Obviously it won't be ideal, but it's not like you won't be able to go down the highway. Unless you're afraid to rev the 4.0 for whatever reason. Just forget about your 5th gear. I have 3.55s and 33s and have no problem sitting in the left lane everywhere but the first 20-25mi of i70 out of denver. When I go to Moab I can run 80-85 all the way from vail pass down. It's just the hills that keep me at around 70.

I don't tow anything though
 
@YonderNorthwest

You're right that ~2-2.5" of SL (depending on the specific rig) is the dividing line between a few parts and a lot of parts.

You can combo with ~2" SL and a 1.25" BL and be in ok territory for 33's. IMHO there's not much value to combo a 1" with a 1.25". Just go with a 2"SL and avoid the issues that come with a BL, but run 32's. 32;s look nice, and they can do a lot of stuff!

One of my rigs was stock height and had 32's. My son dropped off a curb and it bottomed out on the bumpstop bad. Like it was a big noise. There are things you can "get away with," but they are not ideal, and that means you are making compromises. Those compromises will show up in ride quality and functionality. How important is ride quality to you? How important is functionality?

People say, "It works fine for me."

Here's all I have to say to that: "You don't know what you don't know." I've been there before, many times.
 
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lBasket said:
I have the BDS 2.5" lift and 33x12.5 tires. I used to have 31" ko2s at stock height (probably a lil under due to sagging) and all I needed to fix my rubbing was some spacers.

I have no rubbing now with 33s, but you're right it did take a lot of time and parts to get there. I did it at the same time as my tummy tuck though, so it's hard to remember what was "needed" for what now lol.

Regarding the gearing though, you're probably fine. Obviously it won't be ideal, but it's not like you won't be able to go down the highway. Unless you're afraid to rev the 4.0 for whatever reason. Just forget about your 5th gear. I have 3.55s and 33s and have no problem sitting in the left lane everywhere but the first 20-25mi of i70 out of denver. When I go to Moab I can run 80-85 all the way from vail pass down. It's just the hills that keep me at around 70.

I don't tow anything though
Click to expand...

Thanks for the advice. Regarding the regear, one piece I left out was low speed offroad performance while towing the trailer. 1st gear in 4-low doesn't have the torque it used to, and going up hill with the trailer attached requires more throttle feathering than I would like. Maybe 4.56 on 32s would be a happy medium for my needs...
 
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YonderNorthwest said:
Thanks for the advice. Regarding the regear, one piece I left out was low speed offroad performance while towing the trailer. 1st gear in 4-low doesn't have the torque it used to, and going up hill with the trailer attached requires more throttle feathering than I would like. Maybe 4.56 on 32s would be a happy medium for my needs...
Click to expand...

I am working on a offroad trailer myself, so I'm going to learn soon how bad these gears are when towing. But yeah, I'm definitely not saying it's adequate by any means and I don't really know what's best to regear to, others know more on that.

If you're already struggling with 31s though it might be hard for you. I never felt like I had any problems with gearing at 31s like you're saying you do
 
JMT said:
@YonderNorthwest

You're right that ~2-2.5" of SL (depending on the specific rig) is the dividing line between a few parts and a lot of parts.

You can combo with ~2" SL and a 1.25" BL and be in ok territory for 33's. IMHO there's not much value to combo a 1" with a 1.25". Just go with a 2"SL and avoid the issues that come with a BL, but run 32's. 32;s look nice, and they can do a lot of stuff!

One of my rigs was stock height and had 32's. My son dropped off a curb and it bottomed out on the bumpstop bad. Like it was a big noise. There are things you can "get away with," but they are not ideal, and that means you are making compromises. Those compromises will show up in ride quality and functionality. How important is ride quality to you? How important is functionality?

People say, "It works fine for me."

Here's all I have to say to that: "You don't know what you don't know." I've been there before, many times.
Click to expand...

2" lift and avoiding the BL sounds very appealing. Getting to 32s without all of the extra costs sounds like a good compromise for me. What do you think about 4.56 gears on a 5 speed for 32s?
 
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A few things to note: KO2 generally run smaller than the posted size so it is possible that the 31s were closer to 30.5 so that might be why you did not experience any clearance issues. It is possible that whatever 33s you run are closer to an actual 33.

But mainly, the difference between installing 1 inch springs and 2 - 2.5 inch springs is not that much cost-wise. You can always drop your transfer case a bit to fix the driveline angles if you don't want to mess with a SYE. The net may be the same as installing a 1 inch lift but you have more up travel and clearance at the corners. Not to mention the clearance will look better for 33s in my opinion.

If you are committing the effort to regearing for 33s I think it makes sense to do the recommended lift.
 
I have a 2.5" suspension lift and 1" body lift, running 33s. My up and down travel is too weighted to up travel at the moment (I get 5 1/2" without rubbing in the front). But, I do also run a wheel spacer as it is not just the diameter that matters, but also the width. My stock tyres were c.29" x 9.5", whereas my 33s are c.11.5" wide. Without the spacer I would definitely have rubbing on full lock. I am fortunate that even at 2.5" of suspension lift I still have no need for an SYE or any drop of the transfer case, but the 1" motor mount lift I fitted my have helped with that.
 
YonderNorthwest said:
2" lift and avoiding the BL sounds very appealing. Getting to 32s without all of the extra costs sounds like a good compromise for me. What do you think about 4.56 gears on a 5 speed for 32s?
Click to expand...

That would be good gearing for 32’s and the 5speed transmission. You’d want 4.88 for 33’s.
 
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