37” tires - PSI?

Tahoma

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Hello All,

I have 37” tires on my ‘19 JL.

1) What PSI is optimal for on-road driving?

2) what’s the pros/cons of riding at LOW PSI and pros/cons of riding at a higher PSI?

thanks!
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Hello All,

I have 37” tires on my ‘19 JL.

1) What PSI is optimal for on-road driving?

2) what’s the pros/cons of riding at LOW PSI and pros/cons of riding at a higher PSI?

thanks!
Overall weight of the vehicle, wheel width, and weight rating of your chosen tire are the major determining factors for proper on road psi.

You'll probably end up in the high 20's low 30's. Best way to dial in would be a chalk test.
 

SecondTJ

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Do the chalk test. I think you’ll probably find somewhere in the mid 20’s (25-26 psi) ideal for even tire wear
 
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hoag4147

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What brand of tire?
 

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A larger tire has the greater volume of air. When attempting to determine an air pressure number by using the “chalk” method you may find that the tread foot print is nice and flat at a very low pressure. When this is the case the air pressure you come up with may very well be too low for highway service. Even though the “chalk” test gave you a full tread contact patch, at a low pressure the tire may not be stable at highway speeds. The large volume of air can support the load, but the low pressure causes the tire to become unstable. If air pressure is too low for highway service the tire will run hot from over flexing and will cause fast tread wear due to the “squirming”. This overheating can also cause a tire to fail. I have 35s on mine and I use the OEM recommended 37 psi, and my JLUR tracks nice and straight at highway speeds and tire wear is even...
 
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Tahoma

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Lower PSI = even tire wear, lower MPG, longer tire life

higher PSI = uneven tire wear, better MPG, less tire life.

correct/incorrect?
 

rubileon

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Lower PSI = even tire wear, lower MPG, longer tire life

higher PSI = uneven tire wear, better MPG, less tire life.

correct/incorrect?
It's not fair to say "even wear" for lower PSIs... you need the optimal pressure for even wear.

Also...

Lower PSI -> More comfortable on bumpy surfaces, more grip
Higher PSI -> Bumpy and relatively less grip.

The point is, there is a sweet spot. Do the chalk test, etc. but when the tires are warmed up.
 

hoag4147

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Mastercraft MXT 37”
Start at 32 warm and go from there. The D rated will definitely be firm and less PSI will help with ride feel
 
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Tahoma

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I could care less about the feel. I’ve rode it at 42 and rode it at 25. The drive is definitely different, but it doesn’t bother me.

which PSI would help the longevity of tire? A range would be helpful
 

hoag4147

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I could care less about the feel. I’ve rode it at 42 and rode it at 25. The drive is definitely different, but it doesn’t bother me.

which PSI would help the longevity of tire? A range would be helpful
Sorry can’t provide best range but as suggested above the chalk test will provide the best chance of finding an even wear pattern.
 

treyman

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i run 33psi in my 37s. all good after 10k miles.
 

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Depends on the tire too. People with milestar patagonias say to run them alot higher to make them wear evenly. They say chalk doesnt doesnt matter on them. Just what ive read over and over on the milestars.
 

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I run 26 psi on my 37" KO2s. Higher pressure makes my Jeep squirrely on the highway
 

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Depends on the tire too. People with milestar patagonias say to run them alot higher to make them wear evenly. They say chalk doesnt doesnt matter on them. Just what ive read over and over on the milestars.
Yeah, being a hybrid AT/MT with a rounded tread from bead to bead requires sticking to about 35psi. They would flex and grind away in no time, if being run low enough to pass a chalk test. I run mine at a cold 34, warm 36, and they are just starting to show signs of even wear at about 7k miles in.
 
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