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GENERAL GRABBERS AT2's....what PSI should I run them?
http://www.lostjeeps.com/forum/phpBB3/viewtopic.php?f=8&t=26847		 Page 1 of 1
Author:  csukoh78 [ Sat Nov 24, 2007 10:46 am ]
Post subject:  GENERAL GRABBERS AT2's....what PSI should I run them?
I have the 245/75-16 E's.....and I see 80 on the sidewall for max PSI. Should I run them that high??? Sears only inflated them to 35, and the feel a little mushy. I'm thinking 45-50, but 80? What will that do to the weight, handling, tirewear, etc?
Author:  Pote [ Sat Nov 24, 2007 6:50 pm ]
Post subject: 
chalk test it. that's a good benchmark. I'm guessing about 42-44 psi.
Author:  csukoh78 [ Sat Nov 24, 2007 7:18 pm ]
Post subject: 
what exactly is a chalk test?
Author:  JDaPP [ Sat Nov 24, 2007 7:23 pm ]
Post subject: 
I have the same tires and this is what general tires/Continental tire told me

"Please be aware that I am answering your question as an individual and this is not an official position of Continental Tire.

If the original tires' inflation pressure was 33 psi, then the tires must have been "P" metric.

You should be aware that I do not recommend replacing P metric tires with LT metric tires.

Plus this may mean the rims are 6" rims and an LT245/75R16 requires a minimum of a 6 1/2" rim.

But in order to carrying the same load as a P225/75R16 at 33 psi, an LT245/75R16 requires a minimum of 37 psi."



I personally have been running at 60 psi with no problems
Author:  Weegie5 [ Sat Nov 24, 2007 10:08 pm ]
Post subject: 
csukoh78 wrote:
what exactly is a chalk test?


Here's how to do the chalk test. It sounds pretty simple.
http://www.lostjeeps.com/forum/phpBB3/viewtopic.php?p=229990#229990
Author:  jason thompson [ Sun Nov 25, 2007 12:53 pm ]
Post subject: 
Not trying to start a "pissing match" but here it is from the Continental web page
so basically you should run what is stamped in the door if you don't know what your rig weighs and are not
100% sure that you should run XX psi
it is in the orange box mid page

http://www.conti-online.com/generator/w ... ma_en.html
Author:  JDaPP [ Sun Nov 25, 2007 1:19 pm ]
Post subject: 
Continental said exactly that at first, but since it was a different size tire than factory the placard does not necessarily apply. They provided me the info I posted above after a series of emails.
Author:  csukoh78 [ Sun Nov 25, 2007 1:36 pm ]
Post subject: 
Yes, I agree...this is a nonstandard tire for this rig. I am going to perform a chalk test to see what I think, but it sounds to me from the other people I have talked to that 45 is the way to go
Author:  jason thompson [ Sun Nov 25, 2007 5:38 pm ]
Post subject: 
JDaPP wrote:
Continental said exactly that at first, but since it was a different size tire than factory the placard does not necessarily apply. They provided me the info I posted above after a series of emails.



I would have to disagree
I have the MTR's on the KJ and after a chalk test I found that the 3X psi stamped in the door was almost perfect +/- 2psi
what ya'll don't realize is that the marked psi has NOTHING to do with any 1 type of tire but rather how much load your KJ
at max GVW will put on the ground and how a tire will carry that load
as long as the tire you install can carry the load then 32 psi is 32 psi in ANY TIRE
32 PSI is the positive pressure in in the tire compared to the out side world
putting more air than need into a tire will cause it to carry the intended load different
thus you will change the way the tire contacts the ground and change the way it handles

Think about it for a minute
I can run 14 psi in my MTR's out on the trail with no issues ,going slow and that stuff
but if I run the psi out on the highway I would heat them up or even worse pull them off the rim
they will still hold the weight but the shape will change causing more tire to touch the ground
on the other hand the bias ply LTB's on my TJ handle like poop over 25 psi
wear good and all that at such a low psi how so?
I have no clue but I would rather not mess with it
I can also run them at 14 psi and they are only a 6 ply tire

Do what you want but keep in mind that if a tire fails and the MFG can prove that you were running it at a higher or lower psi than what is stamped in the door it will be your fault
road hazard or not the will fall back on what their web page says every time
I have proof from Goodyear svc. center that I was running 32 psi when I had the alignment done 3 days ago
and with the little promo card I have that gets me FREE tire rotation you can bet you stupid that I will go there EVERY time
so that should a tire fail I can PROVE that with out a doubt I did my part to PROPERLY maintain the tires on my Jeep
Author:  JDaPP [ Sun Nov 25, 2007 11:22 pm ]
Post subject: 
I see your point, however I guess we are just going to have to agree to disagree. I am going to have to go with the response I got from Continental tire that went through 6 different Customer service reps and finally to a engineer type who I gave all of the info off of my placard (who I would assume would know more than me on tires, which I admit is not hard). As far as the MFG tire coverage, Continental told me in a earlier email that since they were not the Factory specified tire (or a approved alternate), I probably would have a hard time with any legal issues anyways. But I do appreciate the input and I will probably look into it a little more. Take it easy :D
Author:  jason thompson [ Sun Nov 25, 2007 11:30 pm ]
Post subject: 
JDaPP wrote:
I see your point, however I guess we are just going to have to agree to disagree. I am going to have to go with the response I got from Continental tire that went through 6 different Customer service reps and finally to a engineer type who I gave all of the info off of my placard (who I would assume would know more than me on tires, which I admit is not hard). As far as the MFG tire coverage, Continental told me in a earlier email that since they were not the Factory specified tire (or a approved alternate), I probably would have a hard time with any legal issues anyways. But I do appreciate the input and I will probably look into it a little more. Take it easy :D



OH you can do what you want but the laws of physics do not change and the pressure that you jeep applies to the tires on it will only change with the weight that is in it
and to much pressure in an object will cause it to expand
if the load is not enough to counter that expansion then you will be giving up square inches on the road
witch will be both a blessing and a curse
you will get better MPG
but the tires will wear faster in the center ,expansion has to go some where, and with less contact on the ground stopping will not be as good
simple laws of physics

Jason
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