Ideal tire pressure

ivarr

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Dec 25, 2019
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massachusetts
daily driver 2006 tj believe 2 1/2' lift ( on when i got it, have never measured ) 31 10.5 15's. no offroading except my horrible 700 foot washed out uphill driveway.
abuot 15 miles a day mostly 40 - 45 mph.

where should i have my tire pressure ?
 
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jadatis

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May 7, 2018
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Holland
Need to know more data, but looking at the picture, its a relatively light car, with oversised tires.
So for on road use at 75mph even 20psi might do.

If your speed is never, not even for a minute that 45mph, even lower pressure can do.

But give axle weights in use, and of tires, maxload and kind of tire to determine the reference pressure, and I can calculate a pressure for you. Speedcode of tire would be nice to but not superimportant.

Determining the weigt on axles, or better seperate tires, is the most tricky part in it all.
 
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AaronPaul

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Washington DC
daily driver 2006 tj believe 2 1/2' lift ( on when i got it, have never measured ) 31 10.5 15's. no offroading except my horrible 700 foot washed out uphill driveway.
abuot 15 miles a day mostly 40 - 45 mph.

where should i have my tire pressure ?

Chalk test for the most accurate results in my opinion
 
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MikekiM

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East of Montauk, NY
I followed the advice here and dropped my pressure from 36psi (yes idiot PO set the pressure to 36.. max pressure) to 28 and I verify with chalk test (out of habit). Dramatic improvement in comfort, steering and hopefully wear.

So… is that Edgar Winter? That’s as old school as my chalk test!
 

Mr. Bills

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Do you know what your jeep actually weighs fully loaded with gear and unloaded? If not, you will be guessing at tire pressures, Even the "chalk test" is just a guess because it is a subjective interpretation. It may be a very good guess, but a guess nonetheless.

With the weight of your jeep you can find your "ideal" street pressure using the Rim and Wheel Association Load Inflation Tables, which can be found here:

https://www.toyotires.com/media/pxcjubjs/application_of_load_inflation_tables_20200723.pdf

Another way to get to the same place is as follows:

2006 TJs came with either 30x9.50/15 B 96H tires or 245/75R16-E tires (Rubicons). The factory door stickers called for 29 psi for the 30" tires and 33 psi for the 245/75's, which have a diameter of 30.5" and are similar in size to your current tires but with a greater load rating.

You can use this calculator, which is based upon the data in the TRA Load Inflation Tables, to determine the tire pressure for your 31" tires that best corresponds to the factory recommendations.

https://tiresize.com/pressure-calculator/

When I use the calculator to compare the 245/75R16-E "Rubicon" tires with the 33 psi pressure recommended by Jeep with your 31x10.5R15-C tires, the TRA still recommends 33 psi.

When I use the same calculator to compare the 30x9.50R15-B "passenger" tires at 29 psi that most likely came on your jeep to your current 31x10.50R15-C tires, the TRA recommends 25 psi.

Start experimenting at 25 psi and go up from there as necessary depending on how much heavier your jeep is than the factory curb weight.


PS -

For sand pressure, try this neat trick from Harry Lewellyn, designer of Coyote deflators:

https://www.coyoteents.com/stuck-in-sand/

Tip: Do this in your driveway before you need to know.
 
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