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Discussion Starter · #1 ·
Open Country AT2
Moving to a bigger, wider tire on my 2DR JK
New tires/wheels ordered. Meanwhile, I'm trying to figure the proper inflation?

I tried the Open Country Inflation/Load document with assorted tables, but still can't figure what I should run my Jeep at. I know the Wrangler 2DR JK is lighter than most trucks, so how does this figure into inflation psi?

And I run the beach often, used to air down to 18 (from 35) on my stock 17" Jeep wheel/tires. These new tires are wider, I'm assuming better traction in loose sand.

Any advice, experiences, formulas, etc., much appreciated!
 

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Discussion Starter · #2 ·
Did the calc on the Toyo, way low for everyday driving?

Curb Weight: Wrangler X, Man. Trans. 3760 lbs

Toyo Inflation:
Max load x 4 = 10,140
Div Curb Wt = 37%
x max psi (65) = 24psi
 

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for dd you will be fine at 26-28psi you could probably run at 24 and be ok. I run toyo e rated R/T and Cooper st maxx erated at 26-28psi on my jkr.
 

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Discussion Starter · #4 ·
for dd you will be fine at 26-28psi you could probably run at 24 and be ok. I run toyo e rated R/T and Cooper st maxx erated at 26-28psi on my jkr.
I'll set all 4 tires at different psi, run the chalk test, see which is most even. Run them all that psi. Adjust from there. Thanks.
 

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I'll set all 4 tires at different psi, run the chalk test, see which is most even. Run them all that psi. Adjust from there. Thanks.
chalk test did not work for me on my AT2 or R/T's as they were the same from 12psi to mid 30's psi, I have given up on trying to chalk test 10ply tires.
 

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Discussion Starter · #6 ·
chalk test did not work for me on my AT2 or R/T's as they were the same from 12psi to mid 30's psi, I have given up on trying to chalk test 10ply tires.
Yeah, I can see that... massive sidewalls, at low pressure, might not work for chalk test. But need to start somewhere. Max psi is 65, running at calculated pressure (formula above) is 24, big difference. Reading multiple threads, seems sweet spot is around 28 psi (still low). Any real world suggestions out there?
 

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Yeah, I can see that... massive sidewalls, at low pressure, might not work for chalk test. But need to start somewhere. Max psi is 65, running at calculated pressure (formula above) is 24, big difference. Reading multiple threads, seems sweet spot is around 28 psi (still low). Any real world suggestions out there?
I really doubt anyone on this forum has run more e rated Toyo tires than I have since 2012. I have had probably some where around 8 sets and yes 26-28psi is the sweet spot. I have had the following 245/75-16, 265/75-16, 285/75-16, 285/70-17, 285/75-17,35/12.5-17 in at2 and 35/12.5-17 in R/T. all were best at 26-28psi for DD.
 
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Discussion Starter · #8 ·
I really doubt anyone on this forum has run more e rated Toyo tires than I have since 2012. I have had probably some where around 8 sets and yes 26-28psi is the sweet spot. I have had the following 245/75-16, 265/75-16, 285/75-16, 285/70-17, 285/75-17,35/12.5-17 in at2 and 35/12.5-17 in R/T. all were best at 26-28psi for DD.
Thanks!
 

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Discussion Starter · #9 ·
I really doubt anyone on this forum has run more e rated Toyo tires than I have since 2012. I have had probably some where around 8 sets and yes 26-28psi is the sweet spot. I have had the following 245/75-16, 265/75-16, 285/75-16, 285/70-17, 285/75-17,35/12.5-17 in at2 and 35/12.5-17 in R/T. all were best at 26-28psi for DD.
Jadmt
Do you have a good number for offroad?
Beach... heavy, loose sand?

Thnx
 

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I am not close to any beaches so have no experience in sand. For Moab style jeeping and rubicon trail and dusy ershim type jeeping you are good at ~15psi. When I am in moab that is what I run and I set it there when I arrive and leave it there until I leave. The owner of AEV (he has been to moab more than 40 times and has done Pritchett canyon in a stock jeep so he can drive with the best of them) says anything over 10psi on non bead locks and you are good. I have not been quite that low but if I was in sand I would go that low.
 

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Discussion Starter · #11 ·
I am not close to any beaches so have no experience in sand. For Moab style jeeping and rubicon trail and dusy ershim type jeeping you are good at ~15psi. When I am in moab that is what I run and I set it there when I arrive and leave it there until I leave. The owner of AEV (he has been to moab more than 40 times and has done Pritchett canyon in a stock jeep so he can drive with the best of them) says anything over 10psi on non bead locks and you are good. I have not been quite that low but if I was in sand I would go that low.
Thanks for the info.
I dropped from 35 to 18 with stock 265x70r17 just to give you an idea. So, with the 305x12.5r17 AT2 you would go from 28 to low teens? That scares me a little...
 

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Thanks for the info.
I dropped from 35 to 18 with stock 265x70r17 just to give you an idea. So, with the 305x12.5r17 AT2 you would go from 28 to low teens? That scares me a little...
why? what is your reasoning for being scared to drop down to 15psi offroad? You tell me your reasons and I will tell you why your reasons for being scared are not valid. oh and an "just because" answer does not cut it.
 

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Discussion Starter · #13 ·
The part that made me squeamish was to go down to 10 psi in sand. I'd be afraid to lose a tire. That's just me, it's all good. I appreciate the feedback.
 
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