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Interesting tire pressure observations with 33" KO2's

IOS-XR

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We've got a '21 High Altitude Diesel that I swap tires/rims for winter and wheeling. We put the factory HA 20" wheels and Dueler H/T's on for the summer and a set of '18 JLU Rubicon 17" wheels with BFG KO2's for the winter and some light wheeling.

When we first got the Gladiator if memory serves the factory pressure on the tires was 42lbs. It didn't track very well so per some threads here I dropped the pressure to 36. That really helped the "wandering steering" and over all made it a lot nicer to drive. When we put the 33" KO2's on last fall I assumed that I should run about the same pressure. The tires were "bouncy" and when I was at speed on the four lane I'd get a little shimmy after going over a bump. It would clear up really fast though. I just assumed that was the penalty for running a much taller sidewall off-road tire. I picked up a Fox 2.0 steering stabilizer to put on in an attempt to combat this issue. Haven't done that yet though because I'm lazy/been too busy......

Well this year when we switched tires the dealership I took it to pumped the KO2's up to 44lbs. They rode like rocks! I started dropping them down figuring I needed to get back to 36lbs. I dropped them a bit and hit 40lbs and it was like magic. They track great, aren't bouncy, and I get no "bounce shimmy" on the highway anymore.

I have not tried the chalk test with either set of wheels/tires but I need to do that. I will replace the steering stabilizer in a couple weeks as I've got some new steps to put on anyway but at this point I don't feel like the Jeep needs it.

Anybody else find that the KO2's need to run a little higher?
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ATL_Rubi

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I believe the higher pressure required could also be due to the weight of the diesel. My older jeep, granted it was an 09 2 door on 37s, ran 32 psi on my BFGs and it rode like a dream.
 

jac04

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Anybody else find that the KO2's need to run a little higher?
Interesting. I run a set of JLR take-off wheels & KO2s on my Mojave for the winter. They definitely feel 'different' than my stock Falken Wildpeak AT3Ws. They seem to transmit every little imperfection in the road surface, and they generally don't feel as smooth as the AT3Ws, especially at highway speeds. I have tried lowering the pressure from 37psi down to as low as 30 psi, but they still seem to feel the same.

Maybe I'll try bumping them up to 40psi.
 

Midnight Rider

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3.6L, I have 285/70/17’ KO2’s on stock rims. I’ve found my sweet spot is 34 psi.
 

Snake Eyes

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We use the K02 on our FJ Cruiser and run it right at 40. Sweet spot. It took a lot of time to find that a couple years ago. They are heavy with those sidewalls and it seems the perfect for us at 40.
 

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Jeeperjamie

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On my 35 BFG KO2s I kept them at 38psi and they rode like a dream and wore evenly. My Kanati 37's I have them at 33psi and they ride as good as the BFGs did and are wearing evenly as well. What you are describing seems pretty accurate. Load range is a factor as well on tires and will affect what PSI should be ran.
 

CrazyCooter

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Load inflation table? Larger volume of air = less pressure required to support the weight.

The pressure on the door sticker is for supplied tire and max gvwr. Any deviation from that requires refering to the load inflation table. 42 psi is WAY too high for an unloaded truck.
 

jay21mojave

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AS you posted: CHALK TEST ..FWIW.. I run 35x11.50 17s on 8.5" wheels at 27psi Thanks to the Chalk Test.. Wear is even, Ride is excellent.
 

alpineovernappa

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I run factory spec C rated KO2s on my diesel sport and find that 35 PSI is the right pressure. No handling issues. I prefer a higher PSI but at 40 I found that they were overinflated and would have unevenly worn (centers bald before outer tread). If you have C sidewalls do a chalk test sooner than later to be sure.
 

Barnaby’sdad

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I run factory spec C rated KO2s on my diesel sport and find that 35 PSI is the right pressure. No handling issues. I prefer a higher PSI but at 40 I found that they were overinflated and would have unevenly worn (centers bald before outer tread). If you have C sidewalls do a chalk test sooner than later to be sure.
Agreed. I’ve got C-load 285/70-17 K02’s. I like mine around 36-37 PSI. Get up around 39-40 PSI and they start to feel bouncy/overinflated.

Night and day difference vs. the OE Falken A/T’s, in terms of ride quality and handling. For the folks that have said that they’re terrible vs. stock A/T’s, I have to wonder if they got a bad batch of tires, they’re not balanced, etc.
 

alpineovernappa

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Agreed. I’ve got C-load 285/70-17 K02’s. I like mine around 36-37 PSI. Get up around 39-40 PSI and they start to feel bouncy/overinflated.

Night and day difference vs. the OE Falken A/T’s, in terms of ride quality and handling. For the folks that have said that they’re terrible vs. stock A/T’s, I have to wonder if they got a bad batch of tires, they’re not balanced, etc.
My sport came with factory Goodyear wrangler a/t tires and the change to Rubicon takeoff KO2s was pretty significant in handling, at least for an OEM tire. I think most people are unfamiliar with how much difference an inch or 2 in width can make, let alone more sidewall flex. I’ve loathed the exact same EPA Goodyear tires on every other truck I’ve had, but I actually enjoyed them on the gladiator.
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