Tire pressure for 315/70/17 BFG K02 A/Ts on stock wheels

JAF1

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Getting these installed later this week. I just picked up a 2021 JLUR and wanted to know what others are finding as a good tire pressure to run these at on stock wheels. I can play around with a chalk test later but was looking for a starting point. Hoping someone narrowed it down by trail and error already.

Thanks





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BDinTX

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I put the same size BFG KO2 on with an AEV lift last weekend. The manual recommends 32 - 35 psi so I've been driving around at 32. It rides pretty good but I haven't done a chalk test... now I have something to do this evening : )
 
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JAF1

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Anyone else? I just had them installed last week and am starting out at 32psi.

Thanks!
 

The Last Cowboy

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On stock wheels, 32 is a good place to start. Make sure you are getting the load range C version.
 

jlgolfcart

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Anyone else? I just had them installed last week and am starting out at 32psi.

Thanks!
I had mine installed yesterday they had 36 pounds in them. I did the chalk test today now I have them set at 32 now. I will repeat it at another time mine are on 17 x 8.5 wheels.
 

calemasters

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Getting these installed later this week. I just picked up a 2021 JLUR and wanted to know what others are finding as a good tire pressure to run these at on stock wheels. I can play around with a chalk test later but was looking for a starting point. Hoping someone narrowed it down by trail and error already.

Thanks
I have the stock 17 x 7.5 Rubicon wheels. Last week I installed Falken Wildpeak 315/70R17 AT3W tires and I am running 37 psi.
 

calemasters

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I would recommend doing the chalk test. If you do so you’ll find that you’re probably not touching on an inch on each side of your tire.
You are correct. I will decrease the pressure in 2 psi increments until I get even tread to surface contact. Thanks!
 
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Headbarcode

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I had that exact tire and size on stock wheels, back inbthe beginning. I found 30-31psi to be perfect.
 

jhackathorne

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You are correct. I will decrease the pressure in 2 psi increments until I get even tread to surface contact. Thanks!
I too am running those same size and model of Wildpeaks. Started at 37 and dropped to 30 cold and 32-33 when warm. I let air out same day. I could see at 37 there was an inch not contacting the ground. Haven’t done chalk test but I can see full contact is happening now.
 

tehkayd

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I just received my chalk to do my chalk test.
I also went with the 35 ko2s on the stock Rubi wheels. Driving around warm they are showing about 38PSI from the dealer. I think I will lower down to the 30-32PSI mark but I will give you my findings later.
 

calemasters

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Getting these installed later this week. I just picked up a 2021 JLUR and wanted to know what others are finding as a good tire pressure to run these at on stock wheels. I can play around with a chalk test later but was looking for a starting point. Hoping someone narrowed it down by trail and error already.

Thanks
I have the stock 17 x 7.5 Rubicon wheels. Last week I installed Falken Wildpeak 315/70R17 AT3W tires and I am running 37 psi.
I would recommend doing the chalk test. If you do so you’ll find that you’re probably not touching on an inch on each side of your tire.
You are correct. I will decrease the pressure in 2 psi increments until I get even tread to surface contact. Thanks!
I decreased air pressure to 32 psi. I am not happy with the results.

Pros:
Better straight line on-center steering feel
Better tread to payment contact
Decreased impact harness

Cons:
Increased steering effort
Decreased steering response due to tire sidewall flex when steering left or right
Decreased load carrying capacity (on our road trips, we run near the maximum GVWR)
Low tire pressure warning activated
Higher highway tire temperatures
Increased rolling resistance
Lower fuel economy
Increased tire noise

I have some concerns with the chalk test.
1.) As vehicle speed increases, the tire profile changes and the tire diameter increases
2.) As you drive at highway speeds the tire pressure increases as the tire temperature increases
3.) The tire contact patch changes with speed

Both of the above will have an effect on the tread to road contact pattern. I do not think the chalk test accounts for these changes.

Also, some A/T tires do have a higher less agressive center tread blocks for a quieter road ride, while the outer tread blocks are more aggressive for the trail.
 
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Jeep’n Jay

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I run this exact setup atm and use 30psi cold.
 

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