New Raptor Load Range C 37s?

RubiRed

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For those of you running these tires could you comment on the gearing you are using. Specifically on the two door. I own a Rubicon 2 door and am interested in these tires, and what gears I should consider.
My opinion is that a Rubicon does not need to immediately regear. Drive it for a week and you make the call. Your decision will be dependent on how you intend to use your Jeep.

Just for reference when you go to these KO2 37s on your Rubicon it's going to drive similar (in terms of peppiness) to a stock Sahara on the road. And offroading in 4Lo you'll still have an advantage over stock Sahara because of the Rubicon 4.0 transfer case.
  • Sahara 3.45 gears / 32" tires = 0.108
  • Rubicon 4.10 gears / 37" tires = 0.111
The wheeling video a few posts above, I'm the red 2 door Rubicon on stock 4.10 gears on manual transmission running these KO2 37s. That said, I do want to go to 5.13 and I have an appointment to regear in September. Hope that helps
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jlang

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The Auto 4.10's handle these fine. Is it ideal- no, but I am not in any hurry to re-gear based on performance loss.
 

ChadTx

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Looking to order 2021 Wrangler Rubicon 2 door
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I have the D load 37s KO2s on stock rubicon rims from Discount Tire. Excellent service from DT btw. I was hesitant going to the D load from C and a harsh ride on road but its not! Yay! Aired down to 15 psi in the sand provided excellent traction. I use a super chips flash paq set at 35" tire height and my speedometer is spot on matched with gps speeds! So yes they are a small 37 but im happy with that on stock 4.10 gears. Only added 19lbs to the tailgate and each corner...not bad for the upgrade in rubber!
Is that a mopar 2” lift? How does your ride do at hwy speeds compared to stock?
 

ChadTx

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Looking to order 2021 Wrangler Rubicon 2 door
Just installed the AEV 2" spacer lift yesterday. Some pics to give an idea what these KO2 37s look like with a small lift.

It's one step up from the recently announced Xtreme Recon factory package (35s and 1.5" lift). Honestly would have been a good chance for Jeep to leapfrog the Bronco by offering there choice of 35s or 37s.
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Looks great! How tall is ur rig? Do u notice a performance loss at hwy speeds?
 

RubiRed

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Looks great! How tall is ur rig? Do u notice a performance loss at hwy speeds?
I haven't measured it but it should be right under 4" taller than factory.
  • 2" from the tires
  • 2" from the spacer lift
  • Subtract a tiny bit from the steel bumpers, winch, and heavier spare
The ride is great, it's basically factory with slightly improved bump absorption from the taller sidewalls of the 37s. I went with spacer lift partly because of the cost but also to preserve the factory ride.

Performance loss is felt in city driving. Essentially going to these bigger tires, my Rubicon 4.10 gears feel equivalent to a factory Sahara (3.45 gears on 32" tires). Mine's the 6spd manual and I suspect automatic owners may not notice this as much. On highway I no longer use 6th gear. In 5th gear I don't feel any loss. For Rubicon owners, especially auto, I don't feel like it's a necessity to regear. Definitely encourage to drive it for a week and decide for yourself.

I ended up deciding to regear to 5.13 (my appointment in Sept) because I plan on doing some rock crawling and regaining some of the control while slow crawling the steep stuff. Fewer obstacles where I have to ride the clutch.
 

gone2trackin

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Looks great! How tall is ur rig? Do u notice a performance loss at hwy speeds?
Its
Is that a mopar 2” lift? How does your ride do at hwy speeds compared to stock?
It’s supposed to be 2” but it was more like 3” mopar…. The ride feels the same other than a better view down the road. If anything there is a bit more cush from the higher volume tires. It’s not as quick off the line but I don’t drive like that anyhow. Still quicker than any of the half dozen other Jeeps Ive ever drove. I don’t see 8th gear much with stock 4:10s but I don’t feel it, I just note it on the dash.
 

plex

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I have these 37 KO2 load C put on tomorrow at @Discount Tire, will report back with pictures. Currently on Dynatrac 2" lift (about 1.5" after sag and everything), I also have 4.88 gears so these tires will be handled with ease.
 

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After looking at several different tires/brands I just ordered a set of these from @Discount Tire. I was told a 7-10 day lead time after ordering them late yesterday, but my sales guy called this morning and asked if I was ready to install them as they are in stock here in Houston.

Just need my new Icon Alphas to show up first. Thanks DT and @4xFUN!
 

plex

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Here are the quick results, for reference, the top picture is with 315 KO2 load C and the bottom picture is the new 37 KO2 load C. I have Dynatrac 2" lift but with all the gears you can see in the picture, it is about 1.5" lift at most.

I set the tire size to 35 using Flashcal and it is spot on with highway speed, previously I have it set to 33.5 with my 315 KO2 tires. So essentially this is a "true 35" tire but you get to claim you are going "37".

The ride is exactly the same with my 315 KO2, and I can't tell the difference between these and the OEM 33 KO2. They handle highway and crappy town road very well, plush ride but not soft. I had about 8000 miles on OEM 33 KO2, 25000 miles on 315 KO2, btw I still have 11/32" tread on the outgoing 315 KO2. These tires do last a long time.

I do have 4.88 gears so I see 8th gear all the time, in fact I saw 8th gear too much, it is comical to have 45 mph and 8th gear. Because the weight saving, I think my mpg will take minimal hit by going "37".

Oh I love these tires don't have white lettering, I can't deal with white lettering even if they are facing inward, so kind of bonus point for me.

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plex

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More thoughts on my way home:

I generally found the narrower wheel width, the fattier tires look. 315 KO2 on my OEM Rubi wheels look like it is having a boner, but once I put on AEV Borah (8.5" width) it looks much normal. Now these 37 tires look even slimmer than 35, but could also be the perception of height/width ratio.

These tires ride so nice and quiet you will forget you are in a big box with a sail attached (my old JK used to do that with KM2). Discount Tire inflated them to 37 psi, I did not ask them to air down since I am sure these poor folks were told to just follow door jam sticker. Surprisingly, my Jeep is not wandering around like it supposes to be with high psi.

BTW: I have been a customer of Discount Tire for my whole life, I have never been to any other tire store except once drove my now wife then girlfriend to Sam's to change her tires. I have heard some people saying some Discount Tires can be "horrible", but that must be a very bad location or with a bad manager.

All my experience with DT in numerous locations (Florida, Oklahoma, Ohio) are meticulous, sales are knowledgeable but not pushy, most techs look like high school students but well trained, they go beyond on not scratching wheels and always use torque wrench, they don't do anything other than tires (and wipers), so they have no incentive to upsell you other stuffs.
 

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Here are the quick results, for reference, the top picture is with 315 KO2 load C and the bottom picture is the new 37 KO2 load C. I have Dynatrac 2" lift but with all the gears you can see in the picture, it is about 1.5" lift at most.
Slightly different angles, but you can definitely see the 37's fill the gap more than the 315's. For me, I think these are the "perfect" tire both in size and weight. Can wait for the wheels to come in so that I can get these guys mounted and installed.

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plex

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Slightly different angles, but you can definitely see the 37's fill the gap more than the 315's. For me, I think these are the "perfect" tire both in size and weight. Can wait for the wheels to come in so that I can get these guys mounted and installed.

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I agree this is a better tire for several reasons
First, it is for the 35 too small 37 too big folks, it is also crazy light while still maintain the KO2 all-around profile.
Second, a heavy and true to size 37 opens a big can of worms, axle, steering, tire carrier, etc. With this tire most people can run with stock setup.
Third, thank you Ford!
 

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Most tire manufacturers list the rim width that they used when measuring and listing the inflated tire diameter.

For example; The specification pages for BF Goodrich KO2, TOYO Open County A/T III, and Mickey Thompson Baja Boss M/T tires, just to name a few, list the dimensions of the respective 37x12.5 R17 tires as measured on a 10" wide rim.

This illustration compares the fit of a generic 35" tire mounted on two different wheels:

tire-diameter_17x.jpg
The diameter is not affected according to Tire Rack:

The width of the rim will influence the width of the tire. A tire mounted on a narrow rim would be "narrower" than if the same size tire was mounted on a wide rim.

Note: Because the overall diameter of a steel-belted radial is essentially determined by the steel belts, there is little, if any, change to the overall diameter of the tire due to differences in rim width.


https://m.tirerack.com/tires/tiretech/techpage.jsp?techid=198
 

ArmannB

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might be a noob question here but for people that had both, is there a true size difference between the C and D load KO2s?

I know BFGs generally run "smaller" but curious if everyones observation on the size of these new tires are that they run even smaller than the other KO2 37s
 

jlang

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might be a noob question here but for people that had both, is there a true size difference between the C and D load KO2s?

I know BFGs generally run "smaller" but curious if everyones observation on the size of these new tires are that they run even smaller than the other KO2 37s
Nope C and D are same size. I had the guy a DT pull a "D" out because I had the same question.
 
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