KO2s 35s or 37s?

Learo2000GT

Learo2000GT

Member
Good Morning:
I am trying to decided between 35 or 37 KO2's. I have a 2013 JKUR, manual, with RK 2.5 lift with all the Arms... Guess it is called the X-factor now..... Fender flares, artec armor, and am currently running the BFG KO 35's. I was looking at the specs and the weight of the 37's is not much more then the 35's and the 37 is not a true 37. I don't want to change gears or do any other modifications at this time. What are your thoughts on the stock gearing and other issues that may arise with the 37's vs the 35's. I am thinking because the weight is less that what a Nitto MT would be that I would be fine but not sure about the other issues to take into consideration. My Jeep is a daily driver that does see trail use on the weekends. Thanks in advance. Here are the specs.

SizeDiameterWidthRim RangeMeasured Rim Tread DepthLoad RangeMax LoadMax psiWeight Revs/Mile
LT 35X12.50R17 34.5"12.5"8.5-11"10"15/32"E 3195 lbs65 psi66.5 lbs602

LT 37X12.50R1736.5"12.5"8.5-11"10"15/32"D 3525 lbs50 psi71.3 lbs569


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Welcome to WAL. Give us a wave over in the welcome section.

Regarding your question, based on what you say about being a mild wheeler and having a Dana 44 with what sounds to be factory gearing, I think you will be fine with the 37" K02s. That being said, a set of axle gussets for your C's would be a worthwhile investment if you don't already have them.


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What gears do you have?

The 37's aren't much heavier because those 35's are load range E.
 
I don't have experience with the KO2s but I am running 37" Nitto Trail grapplers with the stock rubicon gears and I definitely lost a little power in the "going up hills" category but it is still manageable. I have 5.13 sitting back home nut am waiting to find time to take the Jeep in. Maybe someone can input on gas mileage between the stock gears and then going up to 5.13s, does it improve or get worse?
 
If you have 4.10s you could get away with it for a while. At some point you'll want to regear though. Everyone who regears says it's the best choice they made. I have 3.73 in my JKUR and am waiting to regear and go to 37s until I can do both simultaneously.

Swampdog is right on adding C gussets.

Also, no 37 tire is a true 37". Don't bother with actual tire size, just look at advertised size.

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http://wayalife.com/showthread.php?p=621404
 
You'll be ok for a bit but you will eventually want to regear. I drove mine with 37s on stock 4.10s and if not for the fact that I do a ton of highway driving, I would have left it.
 
I have 410s and a manual. The 37s are eight lbs less then the 35s nitto trail grapplers. Is it the revolutions being more that has to do with the gear change or the weight. I already have c gussets and front axel gusset. Not apposed to regearing just not in the budget now. The reason I was considering the 37s vs the 35s are the weight not being to heavy and the 37s ko2s are actual size or 36.5 and the 35 is 34.5. The 37s weight 71.3 lbs and the 35s weight 66.5 lbs. the nitto grapplers is a 35 is 81lbs. So I am thinking it is more of a revolution factor for the gearing? KO2s revolution for 37s is 569 vs the 35s at 602. Thanks for the insight.


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I have been thinking the same. I have 35" ko2's with 4.11 on my jkur and it appears to be a nice match. When I had my 35 km2's with same set up my jk was slightly more sluggish. I would say you may be able to slide by with 37's with ko2 but I would bet that a 37 mud with those gears you will feel it. The 37 ko2 matches the same weight as most mud.


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Jtvegas said:
I have been thinking the same. I have 35" ko2's with 4.11 on my jkur and it appears to be a nice match. When I had my 35 km2's with same set up my jk was slightly more sluggish. I would say you may be able to slide by with 37's with ko2 but I would bet that a 37 mud with those gears you will feel it. The 37 ko2 matches the same weight as most mud.


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Click to expand...

So are u thinking of going to 37s? I have 35s KOs right now and I have a tunner and I am able to go over 70 through the mountain passes towing a small enclosed trailer full of stuff.


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Well I do love my ko2's. I have taken them everywhere with almost 25k on them with lots of life left. I have been in all conditions with them and they have performed. My jk has lots of space left in my wheel wells with my lift and fenders so I was thinking of going to 37's to fill in. If I went back to a mud I may stay with a 35. The mud will look more aggressive but the ko2 is a good tire.


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bruggymonster said:
I don't have experience with the KO2s but I am running 37" Nitto Trail grapplers with the stock rubicon gears and I definitely lost a little power in the "going up hills" category but it is still manageable. I have 5.13 sitting back home nut am waiting to find time to take the Jeep in. Maybe someone can input on gas mileage between the stock gears and then going up to 5.13s, does it improve or get worse?
Click to expand...

Same crappy mileage.
 
Learo2000GT said:
Good Morning:
I am trying to decided between 35 or 37 KO2's. I have a 2013 JKUR, manual, with RK 2.5 lift with all the Arms... Guess it is called the X-factor now..... Fender flares, artec armor, and am currently running the BFG KO 35's. I was looking at the specs and the weight of the 37's is not much more then the 35's and the 37 is not a true 37. I don't want to change gears or do any other modifications at this time. What are your thoughts on the stock gearing and other issues that may arise with the 37's vs the 35's. I am thinking because the weight is less that what a Nitto MT would be that I would be fine but not sure about the other issues to take into consideration. My Jeep is a daily driver that does see trail use on the weekends. Thanks in advance. Here are the specs.

SizeDiameterWidthRim RangeMeasured Rim Tread DepthLoad RangeMax LoadMax psiWeight Revs/Mile
LT 35X12.50R17 34.5"12.5"8.5-11"10"15/32"E 3195 lbs65 psi66.5 lbs602

LT 37X12.50R1736.5"12.5"8.5-11"10"15/32"D 3525 lbs50 psi71.3 lbs569

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Click to expand...

I ran the 37s KO2s in my 08 JKU Rubi manual with the stock 4.10 in Colorado with trips on the rocks at least once a month a 5 hr drive to my then fiance on the freeway over vail pass, and 2 week long trips to moab with it. Yes it did suck doing 50 mph in 3rd gear RPM screaming to get over vail pass without letting semis pass me BUT it did just fine. Might stall it a few times on big rocks oh well. I'm sure re gearing would have made a huge difference for the better but I never thought that I HAD TO re gear to go have fun in the jeep. So go 37s for sure!!! Plus it's way more cool to say you have 37s haha
 
desertrunner said:
I ran the 37s KO2s in my 08 JKU Rubi manual with the stock 4.10 in Colorado with trips on the rocks at least once a month a 5 hr drive to my then fiance on the freeway over vail pass, and 2 week long trips to moab with it. Yes it did suck doing 50 mph in 3rd gear RPM screaming to get over vail pass without letting semis pass me BUT it did just fine. Might stall it a few times on big rocks oh well. I'm sure re gearing would have made a huge difference for the better but I never thought that I HAD TO re gear to go have fun in the jeep. So go 37s for sure!!! Plus it's way more cool to say you have 37s haha
Click to expand...

Hey thanks for the info. Did U notice a dramatic decrease in power say around town or on the regular freeway compared to what u had before. Being I have the 3.6 and am at lower elevation I think I would be okay. My main concern is breaking shit but being the tire weighs less then 35MT I think I would be okay. Or is it more of a height issue? I don't think I need to be concerned about driveshaft angle with bigger tires do I? I don't think the angle would change. so when people talk about upgrading axels and what not with 37s is that due to weight increase or is it due to size increase or both? Thanks to all.


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It's the size of the tire that makes the biggest difference. Weight matters but nowhere near as much. The taller tire is basically regearing you with a lower gear ratio. Basically what it will mean for you is kiss 6th gear goodbye. Probably 5th as well. They will only be overdrive, absolutely 0 pull left in them. It will be similar to you 35s on 3.21 gearing.
 
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