Slim357

Probably 3.75-4 will do just fine

Cheep Jerokee

Done a bunch of searching and have not been able to find any specific answers to a question I have...


I found a thread about suggested on road tire pressures but nothing about off road pressures. I see threads about airing down for trails and airing up when going back on road but nothing about how far down people are going for the various types of terrain. I know this will have lots of variables but just trying to see if anyone knows of a general ball park of where to start.


I have a '96 xj currently with LT235/75R15 Cooper Discoverer AT3's. Most of my off roading will be in Southern Arizona.


Thanks in advance!

Lampo85

Finally got tires for my XJ..33/10.50R15 BF Goodrich A/T...very glad i found these. got a deal too..4 for 200..not too shabby

JerrytheJeep

Yeah there's all kinds of variables. You'll probably do fine with 18-15psi at that tire size in sand and rocks.

Cheep Jerokee

Thanks for the reply! I figured it would probably be in the low twenties but wasn't sure about going much lower. Last thing I would want would be to pop a bead loose and have a flat! Still don't know why none of the words and short phrases I used in the searches I did in this forum came up with the info I was looking for. Just got my SJ a couple months ago and haven't been around any experienced off roaders to learn from yet...

sycoglitch

I would stay low 20s with the weight of an SJ. I went down once to 12 with my stock tires. That was my first offroad trip. Since then i went to 17-18. For your weight stay low 20s and you should be great for most terrains.

michaelOH

But if it's super soft sand go down lower I went to 8psi last year at the dunes on my 225/75/ and was unstoppable

sycoglitch

This i agree. If no rocks then go lower. If rocks go higher, meaning towards 20ish.

94XjSport94

20 will have you bouncing around more than 13-15 will on rocks.

McCaffrey

My understanding is if you go much lower than 13-15 you risk popping off the bead, sans beadlocks. I have no 1st hand experience and I don't plan on finding out.

NewKindOfClown

Depends on wheel width, tire width and profile, tire type, wheel speed, and terrain.

sycoglitch

Yup. Everything is a factor when it comes to airing down. Like a 10" wide tire on an 8" wide rim IIRC is a no no for airing down

McCaffrey

I can see into the future and knew this post was coming. It's not my intent to bash your answer but since you basically said, "it depends" without giving a chart then some range for everybody to begin with is a good idea unless it's know for sure for a given tire/size.

NewKindOfClown

My intent was to prevent people from saying, "Do 8psi," without even knowing the variables. Think about how absurd that chart would be when one of the variables is the stiffness of the sidewall, dependant upon your tire of choice.

You gonna make a chart for every tire on the market with every available size and aspect ratio, or should we have the guy asking the question post his information so we can give an educated answer?

McCaffrey

I'd like to do the math for a chart based on quantum mechanics. Sadly we need a Cray supercomputer to run the simulation.