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What should my tire pressure be in my 33's?

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Old 10-17-2013, 12:04 PM
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Default What should my tire pressure be in my 33's?

I have been a road warrior most all of my driving life and have followed a simple rule regarding tire pressure. Look for the max pressure which in most cases was 35 psi and subtract 5 psi, so I would put 30 psi of pressure in the tires.

We’ll I recently bought my second JK and this one came with Kelley Safari TSR M+S LT285/70R17 tires and a 2.5” TerraFlex lift from a local dealer. When I checked the pressure in all 4 tires were set to 35 lbs. Looking at the sidewalls I found that the recommended max pressure was 65 psi. So my normal thinking set in, so I bumped them up to 60 psi. Now I can feel every small crack in the road. I guess I expect the ride to be different but it’s very different.

After reading another thread this morning I found that someone had a max pressure of 50 psi that was recommended by their tire manufacturer however they ran at 35 psi. That seems unusual to me especially since I am on the road most of the time.

Anyone have suggestions of what I need to have my tire pressure at for road use or am I doing it correctly? How about tire pressure for off-road use?

Lee
Old 10-17-2013, 12:25 PM
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I would suggest using the chalk test.
Old 10-17-2013, 12:29 PM
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Originally Posted by SWAMP RAT
I would suggest using the chalk test.
X2 on this.
Old 10-17-2013, 12:42 PM
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Originally Posted by SWAMP RAT
I would suggest using the chalk test.
Will you describe the process?
Old 10-17-2013, 01:02 PM
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Basically, draw a heavy line of chalk across the width of the tire, drive a for a couple rotations of the tire and see where the chalk is worn off. From there you can adjust your pressure up or down.
Old 10-17-2013, 01:03 PM
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Looking at the sidewalls I found that the recommended max pressure was 65 psi.
Recommended MAX pressure the tire can safely handle without exploding. Full size trucks might use that pressure when carrying very heavy loads.

Drop it to 30 or so and then start experimenting. For the chalk test, grab some kids sidewalk chalk and draw a big line across the tread, go for a short drive, and check the chalk pattern that is left. All rubbed off an equal amount = good pressure. Rubbed off in middle but not sides = over-inflated. Rubbed off on sides but not middle = under-inflated.
Old 10-17-2013, 01:05 PM
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Originally Posted by afpilot82
Basically, draw a heavy line of chalk across the width of the tire, drive a for a couple rotations of the tire and see where the chalk is worn off. From there you can adjust your pressure up or down.
Got it. My 6 yr old has plenty to choose from.

Thanks!
Old 10-17-2013, 03:36 PM
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Originally Posted by nthinuf
Recommended MAX pressure the tire can safely handle without exploding. Full size trucks might use that pressure when carrying very heavy loads. Drop it to 30 or so and then start experimenting. For the chalk test, grab some kids sidewalk chalk and draw a big line across the tread, go for a short drive, and check the chalk pattern that is left. All rubbed off an equal amount = good pressure. Rubbed off in middle but not sides = over-inflated. Rubbed off on sides but not middle = under-inflated.
Really? Starting at 30 thanks me nervous. I don't want the tires to fall off the rims. I know they won't but it still makes me nervous starting that low.
Old 10-17-2013, 03:44 PM
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Originally Posted by BLACKJacK

Really? Starting at 30 thanks me nervous. I don't want the tires to fall off the rims. I know they won't but it still makes me nervous starting that low.
I ran the same size tire at 15psi offroad with no issues. With the chalk test on road at 28 to 30 no issues.
Old 10-17-2013, 03:55 PM
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Originally Posted by BLACKJacK
Really? Starting at 30 thanks me nervous. I don't want the tires to fall off the rims. I know they won't but it still makes me nervous starting that low.
The chalk test is the best method to determine optimum tire pressure.

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