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Old 10-14-2017, 12:02 PM   #1
CG
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Air pressure?

These are 33x12.5 16.5 Radial TSX Swampers. What air pressure do you guys run on something like these for your basic bombing round town running down the freeway stuff?

Ive been reading up on it and it seems like some like it a bit softer than the ratings on the tire sidewall recommends. And not just for offroad use.
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Old 10-14-2017, 12:33 PM   #2
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Re: Air pressure?

I'd start with around 32 -35. You want to adjust your pressure so that your tire has even wear across the tread. Too much pressure wears the center, too little, the outside edges.

The side wall is max pressure ( standard load = 35, load range "C" = 50, "D" = 65, "E" = 80.)

The tires on my plow truck are load range "E" but I air down to 35 in the summer. Better ride & better tire wear.
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Old 10-14-2017, 02:05 PM   #3
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Re: Air pressure?

That's where I have been running them, 32-35. I don't drive it enough to have any established wear pattern.

You read something on the board, and then it makes you question what you are doing. So then you google it and see all sorts of answers that make you question it even more. And then you realize you were probably doing it just fine all along ... same as you have been doing it forever and ever lol. Stupid internet haha.
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Old 10-14-2017, 02:22 PM   #4
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Re: Air pressure?

my old k30 with 36" or 38" swamper bias ply is use to run 25psi for best ride and tire wear .

they were 16.5 rim size also .

try the tire chalk test on the tires to help pin point the best psi for any tire on any vehicle . old school trick for finding out pressure .

tire chalk crayon across the tread sidewall to sidewall tread area only .

stright line 1/4-1/3 mile start and stop no turning .

you want even center wear off of chalk with 1/3 almost untouched on outside edges . if just heavy center gone to much air . if center left and outside edges gone or heavy wear its to low air.

did this on mine and 2-3 test drives got me at the 25psi .
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Old 10-14-2017, 05:23 PM   #5
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Re: Air pressure?

Quote:
Originally Posted by sweetk30 View Post
my old k30 with 36" or 38" swamper bias ply is use to run 25psi for best ride and tire wear .

they were 16.5 rim size also .

try the tire chalk test on the tires to help pin point the best psi for any tire on any vehicle . old school trick for finding out pressure .

tire chalk crayon across the tread sidewall to sidewall tread area only .

stright line 1/4-1/3 mile start and stop no turning .

you want even center wear off of chalk with 1/3 almost untouched on outside edges . if just heavy center gone to much air . if center left and outside edges gone or heavy wear its to low air.

did this on mine and 2-3 test drives got me at the 25psi .
That's a great tip, I usually just drive mine for 5,000 miles & then inspect when I rotate! Your way is much faster!
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Old 10-14-2017, 10:29 PM   #6
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Re: Air pressure?

The chalk test works good and i use cheapo sidewalk chalk,It does take a lil time but once you figure out what psi works best write it down somewhere and use forever unless you buy a different brand or size tire then you gotta do it over.
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Old 10-16-2017, 07:09 AM   #7
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Re: Air pressure?

Read the sidewall. If the max pressure is 35-40 try 32. If they are 60 prsi tires try 45 or so. The chalk thing is also a good guide.
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Old 10-16-2017, 10:05 PM   #8
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Re: Air pressure?

Quote:
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Read the sidewall. If the max pressure is 35-40 try 32. If they are 60 prsi tires try 45 or so. The chalk thing is also a good guide.
so if i have a vehicle thats got the wrong load range tires on it and has load E at 80 psi your saying go 65-70 ? ? ? . . . this will make it ride like a cinder block tank .

its a o.k. ish idea but the chalk test is the best . and if you want to get real tech also run them for a bit and use a infa red temp gun to check temps.
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Old 10-22-2017, 08:27 PM   #9
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Re: Air pressure?

I run the 35 12.5 16.5 BFG AT's on my Jimmy about 28 psi. When I was running MT Baja Belteds I ran them around 24. As noted above, chalk test to start and then drive it to see what you like.
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Old 10-22-2017, 09:19 PM   #10
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Re: Air pressure?

My BFG AT radicals like 30 psi. The Pirelli Scorpions I had before that tended to bulge at anything over 25 psi.
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Old 10-23-2017, 09:13 AM   #11
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Re: Air pressure?

I test contact by either wetting tires or run through a wet spot. Then I observe the track it leaves. On dry ground you can wipe a tire down and roll it over the dry ground and observe the tire. I run 55# in my 285/75-16 Goodyear Duratracs on my '72 K2500 and they lay flat across the tread mounted on 8" wheels. The tires are load range E and call for 80# cold pressure. I run relatively light to pretty heavy and they ride nice an stable with weight while not too hard when bed is empty.

You have to go by vehicle vs tire rating vs use with a little bit of tire type/brand mixed in.
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