Tire pressure calculator

[SargeDiesel]

No I appreciate the help, I’m sure you have more knowledge then I do lol. That’s why I turn to the forums.

I'm not so sure about that ha ha ... but thanks.

I have just been down this road before (no pun intended) on another thread... if you ever pass a Loves gas station or similar I think you can weigh you JT for free... just get all tree weights. Some of your local landfills/dumps will do it also (maybe for a 6-pack..lol)

Yes, the forum is great...lots of knowledge... if your not already, you should sign up for the Wrangler JL forum also... lots of the topics and information are similar and interchangeable between the two.

This is my first Jeep and I am learning something new everyday... with all the common issues and the millions of mods, there is a lot to learn ?

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[Jeeper479]

Damn I'm way off then lol I have 35x12.50's and I'm at like 30-32psi. Seemed like any higher pressure made it ride like a log truck.

 

[Shamus]

The numbers the OP used appear to be the Max weights of a Gas JT with max payload.

For reference my JTRD with Clayton 2.5" lift and HD front springs, 35" TKO2s load C, method rims, Diamond back bed cover, FOX 2.5 shocks, full tank of diesel and def, plus myself in the drivers seat was weighed at a Certified Cat scale. The weights were:
Front axle -> 3140 ( diesel adds ~400 lbs of weight over the gas)
Rear axle -> 2880 ( w/ 100 lbs of gear over the rear axle)
Total -> 6020

As others have stated, get it weighed and recompute the pressures or do a chalk test. Could also do both and compare the two. The chalk test will probably give the best pressures to run for the most even tire wear.

 

[ShadowsPapa]

Gotta watch out trying to find specs on the auto blogs and so-called automotive sites.
Often those are standard numbers based on some base model of a specific trim level and you'll find the others to be lighter or heavier. Often they go by either the sport or the Rubicon and if you don't own either of those in a stripped down base model, it won't apply.

I found that my rear tires run cool - never even really warm to the touch, running 37-38 psi when towing with 500 pounds of tongue weight. Otherwise I run lower, around 36.
The sidewalls aren't flexing that much and running 65 mph for 2 hours then stopping and touching every tire - not even warm.
Mine are SL tires. I've always run tires like that for towing and hauling and find if I keep the inflation to match the load, I'm fine. In fact, an SL tire will handle more weight than I should put in the back of a JT.

For reference my JTRD with Clayton 2.5" lift and HD front springs, 35" TKO2s load C, method rims, Diamond back bed cover, FOX 2.5 shocks, full tank of diesel and def, plus myself in the drivers seat was weighed at a Certified Cat scale. The weights were:
Front axle -> 3140 ( diesel adds ~400 lbs of weight over the gas)
Rear axle -> 2880 ( w/ 100 lbs of gear over the rear axle)
Total -> 6020

And my truck is likely lighter, or was. And if the tires are each rated for say, 2700 pounds, that's 5,400 pounds per axle.
If I use your numbers of 2880 and my tires can handle 5400 pounds a pair, I'd have to toss in 2500 pounds of weight to come to the max tire capacity per axle.
If the tire can handle only 2500 pounds each, there's 10,000 pounds for 4 tires, and the truck weighed 6,000 pounds, you'd have to be able to add 3 to 4,000 pounds to the truck to break the total capacity rating of the tires.
I know - that's static load, not accounting for load shifting, banging around and all.
But my point is - how can anyone possibly take a Gladiator to the point of exceeding their tires' weight rating? (unless 4 wheeling, then all bets are off - talking towing, payload and on the road use)

Anyway, it's not hard to figure the tire footprint in square inches, the weight of the truck and the psi you need to run.
In fact you can weigh the truck using pieces of paper, a pencil, tape measure, calculator and tire gauge, and get really close.
I run what the General consumer engineer said I should run based on the tires and weight of my truck.
You need to adjust for seasons there's so many things involved, don't sweat 1 or 2 psi.
But that huge difference - 33 and 40? No way.

 

[Jefe1018]

My approach is much more layman. I've seen people say 37's should only need like 20psi to run correctly, I've tried running as low as 25psi and hated the way it drove. I find my happy medium at 32-35psi. The dealer likes to put my tired to 40psi when I do my tire rotations, not a big deal though.

 

[smlobx]

Back again with some more info.

Yesterday I was watching a video from Trail Recon where Brad discusses what tire pressure to run when off-road. It was pretty basic but I asked him how he determines which pressures to run on the larger tires he normally uses on road and he sent me a link to the site below…

I think it’s pretty accurate as you can not only input your axle weights (either actual or GVRW) and the tire size and load rating. I plugged in a couple of options and thought the numbers seemed reasonable.

What do you guys think?

https://tiresize.com/pressure-calculator/

 

[antwon412]

I guess that calculation chart could be nice if it even had my tires in there. It has no option to enter a 33X10.5 R 17 C load tire - my Kenda Klevers.

 

[LOSTSOS]

Back again with some more info.

Yesterday I was watching a video from Trail Recon where Brad discusses what tire pressure to run when off-road. It was pretty basic but I asked him how he determines which pressures to run on the larger tires he normally uses on road and he sent me a link to the site below…

I think it’s pretty accurate as you can not only input your axle weights (either actual or GVRW) and the tire size and load rating. I plugged in a couple of options and thought the numbers seemed reasonable.

What do you guys think?

https://tiresize.com/pressure-calculator/

This was spot on to what a chalk test revealed for me. I run 30psi on my Toyo Open Country RT Trail based off of several chalk tests, and this calculator was right on it.

 

[ShadowsPapa]

My approach is much more layman. I've seen people say 37's should only need like 20psi to run correctly, I've tried running as low as 25psi and hated the way it drove. I find my happy medium at 32-35psi. The dealer likes to put my tired to 40psi when I do my tire rotations, not a big deal though.

I've had TIRE dealers and Jeep dealers do that 40 psi thing.
I took in a set of 32.8s off a Rubicon to have sensors installed and said while you are at it, just swap the tires/wheels onto my truck. I believe the Rubicon door jamb sticker may say 36 psi? The Overland says 38 for the narrower tires........ I left with 41 psi in those Rubicon take-offs and promptly let them back down when I got home.
I sort of wonder if that comes from decades ago - putting in a much higher pressure to seat tire beads against the rim, then letting it down.......... and they just never let them back down?
But it's not just Jeep dealers that do that bit of crazy high pressure when rotating or installing tires.
Too high is easy -let it down until it's just right. No compressor needed.

 

[RudeJeepin]

I have a set of E rated MT tires. There is an overland tire pressure calculator I found online and plugged in the values. Does this seem appropriate in your opinions? I’m going from stock axle weight

You need the actual weight of your vehicle and not the axle weight rating. Axle weight rating is the maximum weight each axle of the vehicle should weigh when loaded to the max.
Like others have said, set your rig up the way it will usually go down the road. Then get it weighed, preferably get the front and rear axle weights separately.
Then plug those numbers into the calculator. That will be a starting point, different tires (type, brand, model, size) will potentially need different pressures to accomplish the same thing.
Then you can preform a chalk test to finalize your tire pressures. Also tire temps can indicate improper pressures.
Just remember if you add extra weight, as in payload or towing you will need to adjust pressures.

 

[Brahmajoe]

This was spot on to what a chalk test revealed for me. I run 30psi on my Toyo Open Country RT Trail based off of several chalk tests, and this calculator was right on it.

Are the stock tires on a sport p metric?

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