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Discussion Starter #1
Ive got some 325/60/18" terra grapplers and I was just wondering what the best psi is for them? I am currently running 35 but I have heard 47psi?
I emailed nitto but no response yet
 

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It totally depends on the particular truck's weight. Other factors will contribute also, including wheel width, etc.

The best way to find out is to do the chalk test. No two trucks are exactly alike.


You're in the right ballpark though... When I ran similar tires on my ECSB 1/2 ton 4x4, I was running 39-42 in the front and 35-37 in the back.
 

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im running 35 in mine all around. only had them a little over 1000 miles and they havent really shown any wear
 

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I bought a set of BFG All-Terrains a while back from Discount Tire and they put 40 in all 4. I rotated those tires regularly and they only lasted me 10,551 miles.. My current set of BFG's I'm running with 35 and they are having the same problem. I think that was because I had a 5 1/2" blocks in the rear and I wasn't getting traction, but I don't know. We'll hope that the blocks were the reason that my tires were wearing down so quickly. But if I were you I'd run between 35-40..

By the way, what exactly is the chalk test?
 

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I bought a set of BFG All-Terrains a while back from Discount Tire and they put 40 in all 4. I rotated those tires regularly and they only lasted me 10,551 miles.. My current set of BFG's I'm running with 35 and they are having the same problem. I think that was because I had a 5 1/2" blocks in the rear and I wasn't getting traction, but I don't know. We'll hope that the blocks were the reason that my tires were wearing down so quickly. But if I were you I'd run between 35-40..

By the way, what exactly is the chalk test?
my buddy got almost 40k out of his bfg mud terrains and they still have 10k left in them. There's no reason why your a/t's should get that bad of wear. He's already got 10k on his new bfg at's adn they still look brand new.
 

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No I know... I bought a set used with 30k miles on them before these two most recent sets and they lasted me an additional 20k miles after that. It's not the tires, it was something with my truck. Keyword there is was.. I'm hoping removing the blocks solved that but we'll have to wait and see. My Goodyear Wrangler MT/R's are doing the same thing as my all terrains. I know the MT/R's aren't supposed to last more than 20k miles if you're lucky, but they were wearing quicker than that.
 

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jimmy what do those measure out to exactly mounted up? im thinking that size for my moms HD with either the cognito leveling kit or the new 4-6" kit set at 4, my dad and i are still undecided
 

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Bayou Surface Drive, LLC
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its all in contact patch. put some water on the tire and roll it. add/ decrease pressure as needed to get the full tread width touching the surface.
 

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Depends how much you tow/haul. Also which is most important, a smoother ride or better mpg.
 

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Discussion Starter #11
jimmy what do those measure out to exactly mounted up? im thinking that size for my moms HD with either the cognito leveling kit or the new 4-6" kit set at 4, my dad and i are still undecided
id say they are pretty darn close to 33" new.
Mine have 10k on them and they are about 32.75" as best as i can measure. They clear fine with my 3" body and 1" crank
 

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Discussion Starter #12
nitto emailed back:
Dear James P,
The recommended air pressure for your 1999 Chevy K1500 with Nitto Terra Grapplers size LT325/60R18 D is 40 psi (cold) for all 4 tires. We thank you for choosing Nitto Tires.


Thank you,
Anthony Lee
Nitto Technical Department
 

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Discussion Starter #15
perfect, sounds like just the right fit. got any pics of them on there jimmy?
lol everyone wants pics! Im trying to wait till I finish my current round of mods to it. I can snap a pic for ya though
 

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I've been running 40 psi with no problems so far.

For shits & giggles learn me on this chalk test.
 

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For shits & giggles learn me on this chalk test.
You just rub chalk across your tires, drive a short distance, then check to see where chalk is left. If there is still chalk remaining on the edges, then you need to air up some more.

I like the water test too... spray your tires with a little water or drive through a puddle, then look at the contact patch it makes on dry concrete.
 

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40 psi sounds right but it all depends on weight and how wide the wheel is if you run too narrow of a wheel you will wear the center of the tire as will too much pressure and too wide will wear the edges as will too wide thats just what i noticed, i work at discount but then again i'm no expert i just change tires
 
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