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Finally did a chalk test on 37s

19 JLUR Bright Whit3

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Hey all,
I got around to doing a chalk test on my 37s. (Cooper STT Pros on Mopar 8.5in rims ). I had to drop them down to 27lbs/tire to get a full contact patch. Softer ride, but sluggish now. Are you guys with 37s running them this low? They get up to 29ilbs after a good ride.
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PaPasJP

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I run 26 cold on mine.
 

LunchBoxFab

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19 JLUR Bright Whit3

19 JLUR Bright Whit3

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mlebofsky

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Thanks! I wanted to make sure. To clarify the "sluggish" comment, my Rubi is still peppy, I have the opposite of loose steering now. LOL
Agreed. Same here. It's a compromise. I settled on 28 cold, 30 hot.
 

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wibornz

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I run 26 psi cold with Cooper STT PRO 37x12.5 r17
 

kobejo34

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:CWL::CWL:
I run 26 psi cold with Cooper STT PRO 37x12.5 r17
I have 37x12.5x17 nitto grapplers. I think 26 27 is when it will pass the full chalk test they just feel so bouncy and sluggish especially the mile it takes to get out of the 25mph curvy uphill neighborhood. But it does drive better after it's warmed up.

I cant decide between 27 or 30 cold psi. To many choices for OCD + Jeep. :CWL:
 

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26.5 cold for my Rubicon with 37s
 

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:CWL::CWL:

I have 37x12.5x17 nitto grapplers. I think 26 27 is when it will pass the full chalk test they just feel so bouncy and sluggish especially the mile it takes to get out of the 25mph curvy uphill neighborhood. But it does drive better after it's warmed up.

I cant decide between 27 or 30 cold psi. To many choices for OCD + Jeep. :CWL:
Our roads are in such poor shape that at 26psi, it will smooth out the bumps and potholes. I do not get any of the bouncy or sluggish feel. I run the Rancho 9000 series adjustable shocks and the JLUR is smooth as glass. I don't want to say it, but.......It is almost car like to drive on the street with the shocks turned down to the softest setting.
 

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Thinman

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Good thread, very reassuring. Running 37 Pats and had to drop down to 28 cold and still barely missing the outer edges. Was hesitant to drop down further but am still very light being new with plastic bumpers and no real weighty mods outside of the lift, so probably need to be in the 26 range cold.
 

1996cc

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My goal is for mine to never see 30 when hot. Set them anywhere from 25-27 when airing up. This time of year I’m up and down so much (with snow runs), I don’t get too picky cause it won’t be there for too long...
 

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Good thread, very reassuring. Running 37 Pats and had to drop down to 28 cold and still barely missing the outer edges. Was hesitant to drop down further but am still very light being new with plastic bumpers and no real weighty mods outside of the lift, so probably need to be in the 26 range cold.
I run 26 psi with my 37" Pats and they ride pretty good. It doesn't hurt anything to drop psi a little other than you may lose a tiny bit of gas mileage. They will ride smoother and wear more even the closer they are to making full contact.
 

quietpeen

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Good thread, very reassuring. Running 37 Pats and had to drop down to 28 cold and still barely missing the outer edges. Was hesitant to drop down further but am still very light being new with plastic bumpers and no real weighty mods outside of the lift, so probably need to be in the 26 range cold.
I'm shocked you are getting that much contact at 28. I have been running my 37x12.5 Pats on 9" wide rims at 26psi I'm still not getting full contact patch.
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