What psi are you running your 37s??

[Moto_21]

15psi

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[Arterius2]

37" Nitto Trail Grapplers at 34 psi cold, per chalk test

^ This guy here knows what he's talking about.

 

[sourdough]

I'm no expert, HAHA, don't listen to me. My 37x12.5r17 Cooper STT Pros have 35K+ and have even wear at 30/31 warm. Discount Tire does 5,000 rotations. I always ask the tech/service guy, who measures the tread, Hows it looking? Last time in he mentioned it should go to 50K + safely at this pace. The tires are on 8.5" wheels. My experience must be a fluke.

 

[Gorilla57]

15psi

I run 12. Works great.

But, in all seriousness.....these threads are pointless. Each Jeep weighs different, each tire reacts to pressures differently, each wheel width isn't the same, etc. So, person X runs 30, person Y runs 33, person Z runs 28. There is NO formula to tell you what to run in your tires. Each setup is different from the Jeep next to it. Just go out there and do your own experimenting to see what works right...FOR YOUR Jeep.....

 

[gato]

There is a lot of misinformation and adamant claims of fact and expertise by one member on this thread. But the reality is that, within safe parameters, you should set up the pressure that works best for your priorities. For the more popular 37x12.5R17 tires in loads C-E being discussed for our Jeeps, 25-35 PSI cold should be your experimentation range.

Tire pressure, and manufacturer recommendations, try to optimize one or more of the following:
1 - Fuel economy - absolutely the dominant factor for passenger cars by OEMs, but no so much for most of us.
2 - Load carrying ability - important factor for trucks, but no so much for many of us.
3 - Longevity/overheating protection - important factor for fleets, somewhat important for most of us.

The three factors above call for pressures that are on the high side - like the 37PSI from Jeep and the 60PSI+ on a truck.

4 - On road handling - key for sports cars, somewhat important for us
5 - Comfort - important for most drivers on/off road
6 - Snow/Rain/Sand/Ice/Mud/Rock handling - important for many of us

These last 3 factors usually call for lower pressures.

Which one of those factors is more or less important to you should determine your tire pressure.

You may choose to use 35 PSI for a long trip on smooth highways, 30 PSI for around tow mixed driving, 20 PSI for overlanding, 15 PSI for rock-crawling/sand driving. All in one day. Or, you may think that 30 is a good compromise to leave it for on road driving. If you have a super light 2-door you may find that 28 is the sweet spot.



For *ME* and my Jeep (~5,600 lbs 50/50 weight distribution on my typical load) for general road use, 30 PSI all around. Below 30 the ride is more comfortable for sure, but handling on corners start to suffer). Above 30 I get slightly better MPG and crisper turning, but comfort suffers and vehicle gets a little floaty. (and no, I don't do any silly chalk test, as that is immaterial for most modern wide tires)

So experiment and choose what is best for you. If I may suggest a starting point, I'd suggest 30 PSI all around. But that is just a suggestion. Not * the right * pressure - no such thing.

 

[J0E]

6 - Snow/Rain/Sand/Ice/Mud/Rock handling - important for many of us

These last 3 factors usually call for lower pressures.

Great post, I agree with everything but snow. Tall skinny tires work best in most deep snow conditions. You don't want a ski, you want to bite the ground. Sand is probably the most important place to air down. To see what pressure vs. drop/foot-print, use my BigTire39s site.

 

[gato]

Great post, I agree with everything but snow. Tall skinny tires work best in most deep snow conditions. You don't want a ski, you want to bite the ground. Sand is probably the most important place to air down. To see what pressure vs. drop/foot-print, use my BigTire39s site.

Agree. I was thinking about the hard-packed icy-snow typical of what we get in the roads in New england. Fresh fluffy snow is different.

 

[J0E]

Agree. I was thinking about the hard-packed icy-snow typical of what we get in the roads in New england. Fresh fluffy snow is different.

Studded tires are amazing on ice and snow pack. I always had a set of 4 studded tires/wheels when I lived on the mainland. Tall and skinny so they worked in deep snow too.

 

[TCogs1]

I went through a lot experiments and consulted maxxis engineers, unloaded I run no more the 20 psi, no heat no issues. 37x13.5x17, both treps and creepy crawlers. It really depends on tire of interest.

 

[TCogs1]

I went through a lot experiments and consulted maxxis engineers, unloaded I run no more the 20 psi, no heat no issues. 37x13.5x17, both treps and creepy crawlers. It really depends on tire of interest.

I forgot to say, the side walls are 1” thick and at the hammers they break them in at zero, then adjust based on weight - flex. One tires 20 psi is another tires 30psi.

 

[Jammer]

Just installed 37x13.50 r 20 Nitto Mud Grapplers and wonder what others are running for pressure during daily driving. Shop mounted them with 38-40.

If that which I think it is is a E rated Tire that's way too much that's a 10 ply you should be running about 26. I run 28 in my 37 12.:50. Do a chalk test and you'll see but in a 10 ply Tire the Jeep's not heavy enough for that you need to run about 26. That's a very heavy Tire in a 10 ply. Lower and you'll see how much softer the ride is

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