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  #1  
Old 09-28-2005
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Tire pressure

I've been thinking about tire pressures lately and I'd like to ask anyone here for a little help with something that's been bothering me.

Using my BFGs as an example, the sidewall states they are rated at 3042lbs at 65psi. The people at the tire shop inflate them to 32psi per the door sticker (I guess they don't realize that the BFGs are neither the size nor the brand that came on the truck) leading to my question. At half of the air pressure, are the tires then only capable of supporting half of the load?? Meaning that at 32psi the tires can sustain 1521lbs.

I always run my tires hard and while I understand that it will cause the center to wear quicker than the outer edges, I have not noticed any significant difference and it seems to me that higher pressure would reduce sidewall wear by reducing the amount the sidewall flexes. Other than center wear, is there any other reason to NOT run the tires at 85% of the rated max pressure instead of the 50% that the tire shops use??
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Old 09-28-2005
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The "correct" tire pressure is supposed to be the one that evenly loads the contact patch, for most street tires. It is really difficult to determine what that is for a given tire and vehicle, apparently. I've been looking for "definitive" refereneces on how to determine that at home and they just don't exist -- though several people have their own tests to determine it.

The main disadvantage of putting in higher pressure you've already cited: possible uneven wear patterns. Other than that, a rougher ride and different (perhaps better to you) handling would result. I don't see why you can't try it.
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Old 09-28-2005
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Well since you Run a load range D tire, and the door plaquerd says that the tires should be set at 32 for a Passenger rated tire, thats all wrong. With such a stiff tire for a smaller truck youre not gonna get uneven wear unless you are at 20 psi or something rediculous like that and possibly at 65 psi although I doubt it. Whenever I set tire pressures, I like to stick more to the maximum pressure, but unless its a 3/4 ton or heavier rated truck I dont air it to max. I usually air Load range D tires to about 45. now with this higher rated tire you wont be using it to their full load cpacity, because our trucks couldnt handle it anyway, so runnin it lower is smart. It also depends on how much you will be towing. If you tow a lot I would recommend about 45 PSI in the rear and about 35 ish in the front. Like john said, you can test to see how you get the best footprint. Its not very hard. Just spray paint the tread black and drive over a peice of ply wood. Do it at a few different air pressures and see which gives the most even track.

Also running your tire at a percentage of the max PSI will be directly proportionate to the Load capacity to a certain point. that point is going to be probably lower than you want to run your pressure anyway.

Overall, without towing, on a daily driver you should run what feel comfortable to you. Like I said, with such a stiff sidewall your going to have a big range of air pressure that you can run and get good tire wear assuming that you stay on top of your alignment and rotations. Remember, lack of rotations is the NUMBER ONE reason for cupping, feathering, and overall bad wear...
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Old 09-28-2005
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my bfg's on my old truck, i ran 40psi front, and 38 out back.
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Old 09-28-2005
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Just for comparison, the door label pressure recommendation for an unladen Level II is 30 PSI front and rear. That's the factory's compromise setting for ride comfort, handling and traction. Stock LII's use 31x10.50R15 and the rim width is the same as your truck - 7". That should give you a starting point to figure out what's right for you.
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Old 09-28-2005
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Quote:
Originally Posted by rwenzing
Just for comparison, the door label pressure recommendation for an unladen Level II is 30 PSI front and rear. That's the factory's compromise setting for ride comfort, handling and traction. Stock LII's use 31x10.50R15 and the rim width is the same as your truck - 7". That should give you a starting point to figure out what's right for you.


but also the BFGs on yours are only 6 ply tires (load range C)...
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Old 09-28-2005
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6 ply RATED tires, lol -- good luck finding a REAL 6 ply tire short of on a big rig!
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  #8  
Old 09-28-2005
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Originally Posted by n3elz
6 ply RATED tires, lol -- good luck finding a REAL 6 ply tire short of on a big rig!

bah you know what I mean...
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  #9  
Old 09-28-2005
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I do know YOU know it -- but some don't and so I clarify for the greater good...
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Old 09-28-2005
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Quote:
Originally Posted by n3elz
I do know YOU know it -- but some don't and so I clarify for the greater good...


yeah but youre making me look STUPID.




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  #11  
Old 09-28-2005
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use the chalk trick fill tires to max pressure run heavy amount of chalk over tread area then drive back and forth check how the chalk wheres off. then let some air out and add more chalk drive back and forth again. keep doing this until you get an even contact with the tread and the ground. this always worked for me lets you get the best amount of traction and even wear out of a tire.
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Old 09-28-2005
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Quote:
Originally Posted by SUPERGILDO
yeah but youre making me look STUPID.





lol! Can I do that all by myself? Wow...
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  #13  
Old 09-28-2005
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One thing I've noticed for sure is that low tire pressure definitely negatively impacts my fuel economy. I run my tires around 40psi.
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  #14  
Old 09-28-2005
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I hate it when Jiffy Lube sets my tires to 35 and 30. The ride feels sloppy to me. I normally run my BFG ATs at 40-45 psi. I've never tried them at 65, but I might get close one day. Just to see what it feels like.
-- B
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  #15  
Old 09-28-2005
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I ran 40 psi in my stock 31x10.5r15s and there is 11/32 left at 30k miles. I like my truck to ride like a truck.
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  #16  
Old 09-28-2005
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Quote:
Originally Posted by 04lvl2
I ran 40 psi in my stock 31x10.5r15s and there is 11/32 left at 30k miles. I like my truck to ride like a truck.


they are a 35 PSI max dude....
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  #17  
Old 09-28-2005
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Quote:
Originally Posted by Branson
I hate it when Jiffy Lube sets my tires to 35 and 30. The ride feels sloppy to me. I normally run my BFG ATs at 40-45 psi. I've never tried them at 65, but I might get close one day. Just to see what it feels like.
-- B

I hope you dont run em at 65. they max at 35...
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Old 09-28-2005
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The BFG ATs on the Level II's have a max inflation of 50 PSI.
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  #19  
Old 09-28-2005
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Quote:
Originally Posted by rwenzing
The BFG ATs on the Level II's have a max inflation of 50 PSI.

aye you are right on this one bobby. you always kick my ***!!
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  #20  
Old 09-28-2005
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Quote:
Originally Posted by SUPERGILDO
they are a 35 PSI max dude....
Sorry GIL look again. They change from tire to tire, reason I know. The 33s are 35 max.
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  #21  
Old 09-28-2005
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But Gil, it says like 60 or 65psi on the sidewall... Are you sure? 31x10.5R15 BFG All-Terrain KO.
--B
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  #22  
Old 09-29-2005
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Quote:
Originally Posted by Branson
But Gil, it says like 60 or 65psi on the sidewall... Are you sure? 31x10.5R15 BFG All-Terrain KO.
--B

definately not 60 or 65 but very possibly 50...


http://www.bfgoodrichtires.com/asset...rain_ta_kd.pdf
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