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Old 03-21-2015, 09:22 PM
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How much air pressure in 31s?

What air pressure should I have for street driving in 31s? Tires say max 50, right now I have 40psi, I think that's too high giving me a rougher ride than I should have.

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Old 03-21-2015, 09:37 PM   #2
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27-29 psi I think

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Old 03-21-2015, 09:37 PM   #3
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You should run 28 to 30psi in your 31's. The psi on the tire is a Maximum psi the tire is rated to hold at the maximum weight it can carry. Our Jeep weights are no where near that weight.
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Old 03-21-2015, 09:39 PM   #4
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I'm running 28 and may go down to 25-26
The 35 psi mine came with was way too much
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Old 03-21-2015, 09:43 PM   #5
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You should run 28 to 30psi in your 31's. The psi on the tire is a Maximum psi the tire is rated to hold at the maximum weight it can carry. Our Jeep weights are no where near that weight.
so how much should i run in 33's? theyre procomp extreme MT2's to be exact
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Old 03-21-2015, 09:47 PM   #6
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so how much should i run in 33's? theyre procomp extreme MT2's to be exact
26-28psi
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Old 03-21-2015, 10:06 PM   #7
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I've ran 30psi in my 31's for 45k, they ride smooth and wear evenly
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Old 03-21-2015, 10:58 PM   #8
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Keep mine at 28-29.
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Old 03-22-2015, 01:35 PM   #9
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Stock 30" I believe were spec'd for 30psi, check door jamb. I run 30 psi in my 31's, no need to go higher, if anything go lower.
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Old 03-22-2015, 02:03 PM   #10
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I run 28 +/- in my 31 Duratracs. Stock pressure is 32psi but that will lead to uneven wear.
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Old 03-22-2015, 06:21 PM   #11
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Follow the sticker on the door. You can drop by 1-2 psi if you want. I have been through the stock tires and 2 sets of 31 BFG ATs in 197k miles. On my 3rd set right now at about 70% tread. So I have been getting around 50k out of the tires...
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Old 03-22-2015, 06:46 PM
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Dropped to 30psi, major difference in my ride!
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Old 03-22-2015, 08:57 PM   #13
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I run 26lbs in my 31" DC's. Even wear and better tracking. I check pressure once a month.
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Old 03-22-2015, 10:57 PM   #14
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I just got some durtracs from a WF guy and after install set psi at 32 and they run great! Not a harsh ride at all!
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Old 03-23-2015, 01:32 AM   #15
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I just got some durtracs from a WF guy and after install set psi at 32 and they run great! Not a harsh ride at all!
Do a chalk test. They may ride fine at 32psi, but you are not going to get even wear.
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Old 03-23-2015, 08:22 AM   #16
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Do a chalk test. They may ride fine at 32psi, but you are not going to get even wear.
Chalk test is very misleading...
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Old 03-23-2015, 09:03 AM   #17
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Usually start off by what it says on the door pillar. You can go down a few PSI when running larger tires.
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Old 03-23-2015, 09:29 AM   #18
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28 here. gives me proper wear.
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Old 03-23-2015, 11:42 AM   #19
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Chalk test is very misleading...
True, and there are a lot of innacuracies, but it can give a basic idea of the contact patch which can at least help a little bit providing you take into account rim and tire width.
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Old 03-23-2015, 12:42 PM   #20
Knows a couple things...

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Quote:
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Chalk test is very misleading...
X2, it usually leads the inexperienced to underinflate their tires.
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Old 03-23-2015, 01:47 PM   #21
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There are so many variables that weigh into this, I'll just do a short list. Temp, Altitude, Terrain, The tire itself, Air or Nitrogen, Wheel width, Load in the Jeep, How much your Old Lady weighs, Etc. See where I'm goin' with this? Best thing to do is experiment and see what works best for your Jeep, everybodies gonna be different.
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Old 03-23-2015, 02:19 PM   #22
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Take max load capacity for one tire and divide that by the maximum tire pressure. This gives you the amount of weight that one (1) PSI can carry in your specific tire. Take the vehicle weight and divide by 4 to see how much weight each tire must carry. Take this weight and divide it by your original answer of max tire load divided by max tire pressure. This is how much PSI you need in each tire to properly support your vehicle.
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Old 03-23-2015, 02:45 PM   #23
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Example:

Max Tire Pressure = 40 psi
Max Load Capacity = 3,500 lbs
Vehicle Weight = 4,500 lbs

3,500 lbs / 40 psi= 87.5 lbs per 1 psi
4,500 lbs / 4 = 1,125 lbs per tire
1,125 lbs / 87.5 = 12.8 psi

So, in THIS example, each tire must have a minimum of 12.8 psi to carry the vehicles weight.

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