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Upsizing tire lowering pressure
http://www.lostjeeps.com/forum/phpBB3/viewtopic.php?f=8&t=34412		 Page 1 of 1
Author:  Dave08 [ Thu Jul 24, 2008 3:48 pm ]
Post subject:  Upsizing tire lowering pressure
For all the guys running 245/75/16+ tires... Why the 38+ psi idea? Going off suggestion I had my new revo's at 36 , chalk testing showed the tire was over inflated. I've been bumping down and down, currently at 32 and unloaded it is still not fully contacting the road surface for the best wear. After I load mine but and move to college I'll most likely take it down another psi or 2.

So I gotta ask the guys running upsized tires and mostly stock weight, ever chalk tested your tire?

Sure maybe if I ran 40/42 in them they'd get better mpg... But the dang tires are worth a good deal of money too.

Dave
Author:  Bill.Barg [ Thu Jul 24, 2008 4:28 pm ]
Post subject: 
Good question Dave....

Get ready for the full range of answers eventually leading to bashing of one another until the thread is closed by the monitors (this happened to my Radial Rover thread)

The question I have with respect to wear is;

After the initial slight crown of the "over inflated" tire wears down (say 1/16") wont the chalk pattern show full contact, and from then on the wear will be even? Just asking. No claimed expertise
Author:  tjkj2002 [ Thu Jul 24, 2008 5:10 pm ]
Post subject: 
38psi in MT/R's(245/75's and 265/75's) is the sweet spot,best ride and wear.The Trxus MT's in the 265/75 size the sweet spot is 41-42psi.All other tires will be different then the 2 listed and the chaulk test is not a very good gauge anymore for proper psi due to the advancing tech in radial tires.Do not go below the min PSI whick is 32-33psi no matter what tire you got on the KJ,underinflating is a big no-no but don't go to the max sidewall psi either like the guy in the CRD section running 80psi in his tires :roll: .

If you are stock with no added weight(full armor,steel bumbers,rockrails and such) you do not need to go above the recommended 32-33psi,start adding in all that extra weight and you need to up the PSI some.Load range "D" and "E" tires are another ball of wax compared to "P" and "C" range tires.
Author:  Bill.Barg [ Thu Jul 24, 2008 5:25 pm ]
Post subject: 
tjkj2002 brings up a good point

Are you talking load range E or something less?

see

http://marktg.toyotires.com/file/loadinflationtable.pdf page 9 for the LT pressure vs load table.


and

http://www.nittotire.com/assets/safety/ ... Trucks.pdf

For interesting safety info
Author:  RAYMAN975 [ Thu Jul 24, 2008 5:49 pm ]
Post subject: 
yea i got 235-85-16 firestone destination mt, and the tire place put them up to 42psi because its a LT tire, i think the load rating is 'E' but not sure
Author:  Tokyojoe [ Thu Jul 24, 2008 8:08 pm ]
Post subject: 
Just my thoughts......

If you do a lot of rock crawling and aired down a lot, you will most likely wear out the outer part of the tread. To balance it out, inflate so you wear the middle of the tread when on-road. Even wearing.

Simple.
Image
Author:  InCommando [ Thu Jul 24, 2008 8:12 pm ]
Post subject: 
I am pretty certain that your 235/85's are "E" 's. I have never personally seen that size in anything else.
Author:  Dave08 [ Thu Jul 24, 2008 11:54 pm ]
Post subject: 
Bill.Barg wrote:
Good question Dave....

After the initial slight crown of the "over inflated" tire wears down (say 1/16") wont the chalk pattern show full contact, and from then on the wear will be even? Just asking. No claimed expertise


I don't expect a fight... hope not anyway. Your idea would be true, which is why I did it with new tires... Plus my Dad's CRD with stock size tires is clearly wearing the centers of his bridgestone alenza's at 36psi

But using your idea, towards the end of the tires life, you got a tire with a bad center, and ok sides.

I'm sitting with all skids besides the tranny, tow package, but I do tend to keep a pretty clean interior.
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