28 / 25 PSI - Are you kidding me ?

[ScottBeach]

I travel up down and across the state to visit kids. Im just south of your cocoa house. And it is 10 degrees cooler at the house compared to wickem rd. Orlando is a furance. I used a temp gun to check temps. Found 38 psi keeps it lower

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[Jefe1018]

I tried running 25psi on my 37x12.5R17 and didn’t like the way it drove. Around 29-33 psi seems to be the sweet spot for fuel economy and believe it or not acceleration. Maybe it’s in my head but I didn’t like taking turns as sharp at 25psi either.

 

[SargeDiesel]

I travel up down and across the state to visit kids. Im just south of your cocoa house. And it is 10 degrees cooler at the house compared to wickem rd. Orlando is a furance. I used a temp gun to check temps. Found 38 psi keeps it lower

Great idea... I was wondering how people were checking the heat other than by feel... infrared temp gun slipped my mind. Great add !

 

[SargeDiesel]

I tried running 25psi on my 37x12.5R17 and didn’t like the way it drove. Around 29-33 psi seems to be the sweet spot for fuel economy and believe it or not acceleration. Maybe it’s in my head but I didn’t like taking turns as sharp at 25psi either.

No, not just you. I felt the same thing. As of now, I stay around 35 and once heated up or on a hot day they reach 37. But I think this might be a little high.

 

[SargeDiesel]

I travel up down and across the state to visit kids. Im just south of your cocoa house. And it is 10 degrees cooler at the house compared to wickem rd. Orlando is a furance. I used a temp gun to check temps. Found 38 psi keeps it lower

On a side note, may I ask what you are involved in, visiting the kids and all ? If you don't want to reply publicly, PM me.
I am very familiar with wickem Rd. Traveled it many, many times. Lived in the area for over 40 years.

 

[jav_eee]

You don’t have to do the chalk test with chalk. Just look at the tread. It should be noticeable where the tire is making contact with the road and where it isn’t. Notice how the inner portion is lighter/dirty and the outer edge of the tread is darker/not dirty:

 

[Vtur]

I'm around 30-31 cold on 37s AT. The contact is up to about 1/4" from the edge of the shoulder. Any lower and they runs a bit too hot for my liking.

 

[Jeeperjamie]

I keep mine at 34 psi cold, chalk test says they are wearing even and I rotate them every oil change, which is 8500-9,000 miles. I've got 42,000 miles on my Kanati Trail hogs and probably have about 3000-4000 more miles left in them. 37-12.5 17's

 

[Mr.Wilson]

Anyone running 37x12.50r17 Milestone Patagonia MT’s?
If so what psi are you setting them at. I just put them on and set them at 36psi but I definitely find it a bit squirrelly on the highway.

 

[Marlinvx]

The diameter of the tire is somewhat irrelevant. It is the ply/load range and tread width of the tire that matters. On a heavy-rated tire (E range), I was running 27psi. On lighter C-range tires, I run 35ish.
If you run heavy range tires at high pressure, your jeep doesn't weigh enough to get full tread contact, then you hit a bump or a rut, and all of a sudden, that tread is full contact, which adds drag, which will pull you in that direction. It is terrifying at freeway speeds. You will also risk wearing just the center of the tread out.
Too low, you end up wearing the sides of the tread and you are missing some stability for at speed cornering...
Chalk test them and be done with it. It varies too much tire to tire and by vehicle setup.

 

[bleda2002]

Here in Alabama, we get some hot summers as well... typically hotter than my Cocoa Beach house in Fl. But there is always a breeze on the ocean.... it does get very hot in Orlando and inland. How do you determine the additional PSI vs. Higher Temperature ?

I watch the tpms on long highway drives to gauge heat. Hotter the tire, higher the pressure, it's normal for it to go up 1 or 2 psi, any more than that and you are getting excess heat.

 

[Eric Kern]

28 psi is getting in the area where you wanna be. A vast majority of the JKU/JLU crowd swears by 28psi on their 35s (which I can also confirm on my JKUR with 35 Duratracs. My JTR has same tires, chalk test showed good around 31, ran them down to 28psi, no difference in ride, try to keep them at 30 cold (squeezing out those extra pennys of gas!!!), no abnormal wear yet, 10k mi. I know 35s ain’t 37s, but just pointing to you should be much less than the factory 37psi.

 

[CrazyCooter]

The required PSI has little or nothing to do with the actual load range of a given tire......This is all about air volume.

Obviously more volume carries more weight and this is why a LRE tire can carry more that an equally sized passenger rated tire. If one wishes to carry more weight on an equally sized tire, obviously volume has to increase by increasing pressure however the tire has to be build to withstand the higher pressures. This is where the LR C, D, E, F, G, H, etc... comes in to play.

If one actually examines a manufacturer's load inflation table this is easy to see. A fully loaded/overloaded Gladiator on a 37X12.50R17 can easily be supported on less than 25psi! Toyo's table indicates that 2,150lb can be supported on a single 37x12.50R17 tire @25psi, so simple math shows us that 4,300lb can be carried on a single axle.

Now they do not seem to to take into account wheel width, but in theory an 8" wide wheel has MUCH less volume than a 10" wheel. I theory a wider wheel equals more volume so the pressure could possibly be reduced for better grip, life and ride.

On my own stuff I would just adjust as I feel is needed. On a client vehicle, I always set air pressure toward the high side since I have no control over what the end user will do with the vehicle and safety/liability is a factor.

So in summary........The pressure printed on the door sticker is ONLY for the OE sized tire and weight ratings. Increase tire size or exceed GVWR would require a tire pressure adjustment.

All that said, I found 25/23 psi for my accessorized truck on 37x12.50's and 17x8.5 to be the sweet spot. Now that I'm on 38x12.50's I have found 22/24 to be the best I can do as the Tazer will not go any lower on the tpms setting and I can't get the Alfa OBD to adjust all TPMS settings keeping the light and warning off the dash.

 

[Proximo]

Anyone running 37x12.50r17 Milestone Patagonia MT’s?
If so what psi are you setting them at. I just put them on and set them at 36psi but I definitely find it a bit squirrelly on the highway.

My Pat's are happy at 30-32 on road, 15 off-roading

 

[SargeDiesel]

I watch the tpms on long highway drives to gauge heat. Hotter the tire, higher the pressure, it's normal for it to go up 1 or 2 psi, any more than that and you are getting excess heat.

Thanks, the answer I was looking for. I watch mine also, I don't think mine have ever raised over 2 psi when highway driving, maybe I'm closer to the proper psi , than I think I am. It's been raining last couple days, so no chalk test yet.

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