What air pressure should I have for street driving in 31s? Tires say max 50, right now I have 40psi, I think that's too high giving me a rougher ride than I should have.

27-29 psi I think

You should run 28 to 30psi in your 31's. The psi on the tire is a Maximum psi the tire is rated to hold at the maximum weight it can carry. Our Jeep weights are no where near that weight.

I'm running 28 and may go down to 25-26
The 35 psi mine came with was way too much

so how much should i run in 33's? theyre procomp extreme MT2's to be exact

26-28psi

I've ran 30psi in my 31's for 45k, they ride smooth and wear evenly

Keep mine at 28-29.

Stock 30" I believe were spec'd for 30psi, check door jamb. I run 30 psi in my 31's, no need to go higher, if anything go lower.

I run 28 +/- in my 31 Duratracs. Stock pressure is 32psi but that will lead to uneven wear.

Follow the sticker on the door. You can drop by 1-2 psi if you want. I have been through the stock tires and 2 sets of 31 BFG ATs in 197k miles. On my 3rd set right now at about 70% tread. So I have been getting around 50k out of the tires...

Dropped to 30psi, major difference in my ride!

I run 26lbs in my 31" DC's. Even wear and better tracking. I check pressure once a month.

I just got some durtracs from a WF guy and after install set psi at 32 and they run great! Not a harsh ride at all!

Do a chalk test. They may ride fine at 32psi, but you are not going to get even wear.

Chalk test is very misleading...

Usually start off by what it says on the door pillar. You can go down a few PSI when running larger tires.

28 here. gives me proper wear.

True, and there are a lot of innacuracies, but it can give a basic idea of the contact patch which can at least help a little bit providing you take into account rim and tire width.

X2, it usually leads the inexperienced to underinflate their tires.

There are so many variables that weigh into this, I'll just do a short list. Temp, Altitude, Terrain, The tire itself, Air or Nitrogen, Wheel width, Load in the Jeep, How much your Old Lady weighs, Etc. See where I'm goin' with this? Best thing to do is experiment and see what works best for your Jeep, everybodies gonna be different.

Take max load capacity for one tire and divide that by the maximum tire pressure. This gives you the amount of weight that one (1) PSI can carry in your specific tire. Take the vehicle weight and divide by 4 to see how much weight each tire must carry. Take this weight and divide it by your original answer of max tire load divided by max tire pressure. This is how much PSI you need in each tire to properly support your vehicle.

Example:

Max Tire Pressure = 40 psi
Max Load Capacity = 3,500 lbs
Vehicle Weight = 4,500 lbs

3,500 lbs / 40 psi= 87.5 lbs per 1 psi
4,500 lbs / 4 = 1,125 lbs per tire
1,125 lbs / 87.5 = 12.8 psi

So, in THIS example, each tire must have a minimum of 12.8 psi to carry the vehicles weight.