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Old 10-01-2010, 04:59 PM   #1
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Questions about tire pressure

Hi...I am new to this and also new to Jeep world. I just bought a 2000 Wrangler 4.0 two weeks ago. I am planning to use it as my hunting rig. I also put on BFG AT 31x10.5x15 last week.

1. What tire pressure should I be using when I am out on the trail for all 4 tires? The trail is most hard compacted dirt, some gravel trail, and some muddy trails.

2. What tire pressure should I be using on freeway or everyday driving?

Thank you for any advice.

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Old 10-01-2010, 05:13 PM   #2
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31" tires are a tad larger than the factory installs so you would use a tad lower air pressure than is indicated in your owner's manual or on the door jamb. 30 psi is fine for 1-2 people, perhaps 31-32 psi if it's a bit more loaded than usual.

Offroad, you can take it down to 15 or so psi for getting to your hunting locations. For tougher trails, you can take it down to 12-13 psi without problem. Carry an air compressor so you can air back up before getting back onto the highway. 25 mph is the max speed for aired down tires, any faster than that will heat them up which can possibly cause a tire failure.

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Old 10-01-2010, 05:17 PM   #3
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I have the same tires just a little bigger, they are awesome.... But I usually do the max and have never gotten stuck in mud and the gas milage sucks either way so.... but I love the tires just mine are so wide when I hit and puddle in the road at 35 mph I hydro plane so be careful for that haha
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Old 10-01-2010, 05:18 PM   #4
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But I don't off road too seriously so I'd go with Jerry haha
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Old 10-01-2010, 05:22 PM   #5
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.... But I usually do the max
Do you mean you inflate your tires to the air pressure molded onto the sidewall?
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Old 10-01-2010, 05:23 PM   #6
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Quote:
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Do you mean you inflate your tires to the air pressure molded onto the sidewall?
Yes, I should has made that more clear. Thank you haha
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Old 10-01-2010, 05:26 PM   #7
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Thank you guys for the advice. I will make a mental note of that...maybe not, I will write it down.
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Old 10-01-2010, 05:30 PM   #8
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Yes, I should has made that more clear. Thank you haha
The air pressure molded onto a tire's sidewall is never the correct air pressure to use. That air pressure is only the tire's maximum safe air pressure which is only to be used when the tire is supporting its maximum safe weight. The usual load for a tire is approx. 50% of its max safe load limit which gives a safety margin.

The vehicle's weight is what dictates the correct tire pressure so you can see, based on that, that the air pressure molded onto the sidewall can't be the correct air pressure for all possible vehicle weights.

Plus airing a tire up that high will cause uneven tire wear.

I dunno what tire size you run but let us know and we can give you a more realistic tire pressure to try. Which will also improve the ride of your Wrangler.
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Old 10-01-2010, 05:52 PM   #9
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I just checked it and it's still at 34 and I run 33s haha wow I feel like a rookie haha and they aren't tuning uneven or bubbled out at all but if you have any other suggestions please tell me haha
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Old 10-01-2010, 06:22 PM   #10
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For 33x12.50 tires, 26-28 psi is about right.
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Old 10-01-2010, 06:36 PM   #11
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So what would you think about 35" tires?
Have you tried the chaulk test? Draw a line across each tire and drive about a 100 feet and look at them. if the chaulk is gone only in the center then it is over inflated, if only gone on the sides it is under inflated.
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Old 10-01-2010, 06:40 PM   #12
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I run 25-26 in my 35x12.50 tires, I sometimes bump it up to 28 if I'm about to take a long highway road trip in hopes of a little better mpg.

The chalk test can be helpful but only when used as a guide and not the sole determining factor for what air pressure to use. Way too many people have underinflated their tires based on how they interpreted their chalk test results.
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Old 10-01-2010, 07:32 PM   #13
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Over inflation will lead to the center of the tire wearing out faster than the outside edges.
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Old 10-02-2010, 03:02 PM   #14
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Tire pressure

When I had stock tires on the Rubi (245/75/16) I ran 30 on highway, 15 off road. On my 315/75/16 I run around 20 on the road and 8/10 off road, sometimes 22-24 on a road trip trying for a little less rolling resistance. Ron
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Old 11-18-2010, 06:03 PM   #15
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What about 33x13.50x15 Toyo open country... Day to day pressure, long haul pressure(long highway trips) and fun time pressure please...... Thanks
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Old 11-18-2010, 06:09 PM   #16
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Quote:
Originally Posted by Jerry Bransford
I run 25-26 in my 35x12.50 tires, I sometimes bump it up to 28 if I'm about to take a long highway road trip in hopes of a little better mpg.

The chalk test can be helpful but only when used as a guide and not the sole determining factor for what air pressure to use. Way too many people have underinflated their tires based on how they interpreted their chalk test results.
Hi Jerry, what do you recommend for
31x10.5 on a four cylinder tj?
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Old 11-18-2010, 07:25 PM   #17
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Hi Jerry, what do you recommend for
31x10.5 on a four cylinder tj?
29-30 is about right for that.
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Old 11-18-2010, 07:48 PM   #18
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BF 32-10.5/15,s 35 psi all the time .

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Old 11-18-2010, 07:57 PM   #19
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BF 32-10.5/15,s 35 psi all the time .

BANGER
35 psi is too high for that size tire, don't use the air pressure molded onto the sidewall as your indication of what to inflate it to. The air pressure molded onto a tire's sidewall is only meant to show its maximum safe air pressure which should only ever be used if the tire is somehow carrying its maximum rated weight. Since all our tires never even get close to carrying their max safe weight limit, the sidewall's air pressure will never be the correct air pressure.

For a 32" tire carrying a vehicle with the typical weight of a Wrangler, 26-27 psi is about as much as it should be inflated to.
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Old 11-18-2010, 09:22 PM   #20
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Quote:
Originally Posted by Jerry Bransford
29-30 is about right for that.
Thank's
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Old 11-19-2010, 06:42 AM   #21
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For highway use: (vehicel weight / combined max load of tires) x max psi on side wall = correct psi to run

On my LJ with 33x10.5x15s:
vehicle weight = 4800lbs
combined max load of tires = 10400lbs
psi on sidewide = 50psi

(4800 / 10400) x 50 = 23 psi

You can split this front and rear for more accurate numbers. If you load up for trips you can re-do the math.

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