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Unread 09-25-2013, 01:55 PM   #1
Ed209
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Minimum tire pressures for airing down

What would be the minimum pressure you could run in a 31x10.5R15 on a 15 x 8 wheel? How about a 245/75x16 on a 16 x 8?

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Unread 09-25-2013, 02:00 PM   #2
biffgnar
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Depends on what type of wheeling you are doing with it, but generally I'd say you should be comfortable in the 10-12 range.
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Unread 09-25-2013, 02:00 PM   #3
drandersoninc
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Don't have exact examples for those specs, but for my 35" on 8" wide rims with no bead locks I run 9 lbs.
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Unread 09-25-2013, 02:09 PM   #4
Gordon-0
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Quote:
Originally Posted by biffgnar
Depends on what type of wheeling you are doing with it, but generally I'd say you should be comfortable in the 10-12 range.
I hate this answer, but it is true.
You are safe at 10-12.

Of course you can go lower but you will have to experiment with it.

You will know you are about at the limit when the tire starts burping air when you are fighting to turn the wheel. If you aren't doing rocks, there isn't much benefit to going lower than 10 anyway. You lose ground clearance fast.
Rocks are a different story. 3-4psi with double bead locks is the name of the game. Oh. And 33" or bigger tires will help a lot.
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Unread 09-25-2013, 02:25 PM   #5
Ed209
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Quote:
Originally Posted by Gordon-0 View Post
I hate this answer, but it is true.
You are safe at 10-12.

Of course you can go lower but you will have to experiment with it.

You will know you are about at the limit when the tire starts burping air when you are fighting to turn the wheel. If you aren't doing rocks, there isn't much benefit to going lower than 10 anyway. You lose ground clearance fast.
Rocks are a different story. 3-4psi with double bead locks is the name of the game. Oh. And 33" or bigger tires will help a lot.
Are load range C tires better for airing down than the stiffer sidewalled load range Es?
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Unread 09-25-2013, 02:30 PM   #6
Gordon-0
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Quote:
Originally Posted by Ed209
Are load range C tires better for airing down than the stiffer sidewalled load range Es?
Some people say yes, but I don't know for sure. It depends on the weight. I guess in theory, the stiffer belts would help hold the bead on but I really don't know for sure.
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Unread 09-25-2013, 06:32 PM   #7
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The only thing that holds the bead to the rim is the internal pressure in the tire. (And to a very much less extent, the friction of the tire bead on the rim. I have seen guys who put soapy water on the tire and rim when mounting the tire experience a bead loss in circumstances that surprised me).

I think the sidewall stiffness means zilch. When an C or an E rated tire is flat, its still a pancake. And, since you can pinch a C or an E rated sidewall together with your fingers, I don't think it makes any difference at all in de-beading.
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Unread 09-25-2013, 06:58 PM   #8
KKiowaTJ
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I have 12.50's on 8" wheel and can comfortably run 5-8lbs all day on trails. You don't gain much by dropping it a few pounds, Its just low tires with no extra bite. Yea you can pop a bead, But just as easy at 10psi too.

If you want to find the absolute minimum you can go, Get a paint marker and mark the wheel and tire at the bead, Keep dropping a pound starting at 8psi until it slips and spins the wheel inside the tire. When that happens add a pound or two back and that's you're rigs lowest.

With a heavier load range, You might have to run single digit numbers to even get a good bite and squat from the tire. Just have to play around with it and find its sweet spot. Good luck
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Unread 10-05-2013, 06:01 AM   #9
Trendsetter75
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How much to air down on 15x8 with 33x12.50 doing mild offroading (no Rocks)?
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