How to determine the correct tire pressure for your Jeep Wrangler TJ

[Mr. Bills]

Rather than rely upon a knee jerk reaction that "45 lbs is way too high" or "Load Range E is way too stiff," one way to determine the "correct" air pressure for a specific tire size and load rating on a particular vehicle is to weigh your jeep fully loaded and then look up your tire size and load rating on the Rim and Tire Association Load Inflation Table, reprinted here by Toyo Tire:

https://www.toyotires.com/tires-101/tire-load-and-inflation-tables
https://www.toyotires.com/media/2125/application_of_load_inflation_tables_20170203.pdf
It will be relatively easy to extrapolate the tire pressure necessary to support the weight of your jeep. In the case of a 315/75R16-E tire ("metric 35"), at 65 psi it will support its full E load rating of 3860#, at 50 psi it will support 3195# (D), and at 35 psi it will support 2535# (C). [See page 22 of the chart.]

Depending upon the actual weight of your jeep you may find that 24-26 psi is the extrapolated pressure most appropriate for a "metric 35" E load rated tire on your jeep, which not coincidentally is the common wisdom for street pressure for that size tire on a TJ/LJ.

 

[Painfultruth]

A piece of chalk works well too, especially if you don’t have access to a scale.

 

[Mr. Bills]

Note:

The first post in this thread is reprinted from my comment in this thread: https://wranglertjforum.com/threads...ed-tire-lead-to-abnormal-wear-patterns.30656/

I do not contend that extrapolating inflation values from the Rim and Wheel Association Load Inflation Tables is the only "correct" way to determine air pressure for a particular size and load rated tire on a particular vehicle, or the best way, or any other descriptor one may choose to apply to the method.

It is simply one way to do it

 

[Jerry Bransford]

A piece of chalk works well too, especially if you don’t have access to a scale.

The use of chalk to figure your tire pressure rarely produces anything but an underinflated tire if you don't know what an appropriate pressure would be to at least get close. TIres are rarely designed to have all of their tread on the ground so looking for even chalk wear after driving and then adjusting air pressure to get it even across the tread is likely to produce and often severely underinflated tire.

I used to think the chalk test had to be a valid method but now I believe it's mostly an old wive's tale unless you really know what you're doing around tires and tire pressures and know what to look for.