Help with tire psi!

[dannymalkin]

I recently bought some 35/12.5R15 tires and have them on 15x8 inch wheels.

The shop originally set the psi around 40. I am trying to get the best tread wear possible, and after repeating the chalk test several times they are now at 28 psi and chalk is still showing on the edges of the tread.

My question is can I safely go lower on the psi until the tread is even? Anyone else have a simiar narrow rim/wide tire setup that can chime in?

Also here is a picture after driving a mile. Chalk is yellow on the outside left and possibly the inside. Not the best pic sorry

 

[MedixJK]

I have heard, although not comfirmed, that with a narrow rim, 7.5 or 8, that it is hard to get a 12.50 tire to wear evenly.

Add: i need to do mine again too. Ill try and post up tomorrow.

 

[07JKSahara]

I have a two door with 35s. I run 24 around town. That's the best wear I get. You're fine below 28

 

[2013rubirick]

I run 26psi in my 40's and they are perfect.

 

[Clem319]

I have 35's and run 28psi

 

[Armydog]

Running 35x12.5 MTs. On stock width rims, at around 18-20 psi...... Seems to be wearing pretty evenly. Chalk shows full tread contact...

 

[dannymalkin]

Thanks for the help everyone. I did some adjusting and here is another picture. This tire is at around 21 psi and it appears the edge of the tread isn't even touching still...

 

[83jeep]

Here is a good write up on tire pressure when you are not sure to run.
http://www.aawen4x4.com.au/?option=com_content&view=article&id=1:4psi-rule&catid=2:current&Itemid=7
It works for on road quite well.

Here is a write up I did for that test, the chalk methed and the 75% method for off road. 2 different tire types. Stock JK BFG MTS and q78 swampers.
http://gitout.com/showthread.php?1199-Optimal-PSI-via-the-4-PSI-rule