LsSaha07

@ 50 psi or over you are just asking for a blown tire on a pot hole or curb.

Keep this in mind, if your old 285 (or whatever size ) was running great @ 30psi, why would you double the amount on a tire that is only a couple of inches bigger? Imagine you had 10 lbs of cotton, and 10 lbs of iron, even though they are different in size, they still weight equally, same goes for 30 psi in a 285. Or 30 psi in a 37"

I run 37" km2, when I hit long drives, I air up to 35 psi. I've done 40 psi, only to air down back after a couple hundred miles, don't like feeling every little crack on the road.

In the city I am always @ 28 psi, driving up to 75 mph with no worries whatsoever.

Ncb

Max pressure is required when you're nearing the max loading. My 35s have a max load of 3,000 pounds and max pressure of 50 psi. The only reason to ever air up near 50 psi is if the tires were on a large/heavy pick up truck. On a JK the max pressure is overkill. If you truly understood pressure and weight loading you wouldn't be nervous about tires slipping or falling of the wheels. I wouldn't air up any higher than what's on the tire placard on the door jamb.

EHarris

Just air them anywhere between 28-32. It's not going to matter really all that much in that range. Cold mornings and hot days the pressure changes anyway. I run 305 which is just a wider 33 and I'm right around 30. Tires are wearing fine. They are KM2's.

Bkeeper

I run Kelly TSR 285s on my JKU with a 2.5 RK lift, heavy bumpers front/rear, winch and lots of under armor. Best "all around" pressure for them is 32psi cold. When they heat up pressure goes up 3-4 psi. I would love to run them at 32psi hot, except when they cool after running or on a cold morning the pressure drops to 28-30psi and the dang tire pressure warning comes on. Until I can get around to having the pressure warning set to under 15psi I run mine at the pressure stated above, 32psi cold.

Wear after 7k is next to nothing. Mpg at frwy speed (70) hovering around 18.5. Interestingly running these tires at 38-40 psi, frwy mpg is right at 20, but the ride is horrible.

Wr@ngler00

Im pretty sure its stated on the sidewall of the tire. No?

zstairlessone

The air in the tire is supporting the load (Jeep + everything and everyone in/on it). It does this by exerting enough FORCE to hold everything up. Force is PRESSURE x AREA. With smaller tires you need more pressure to give you the same force. Think about a road bicycle tire - small and roughly 100 psi, now move to a larger mountain bike tire (with a heavier bike) 40 - 60 psi. As your tire gets larger the same pressure will carry more load. You also have to look at sidewall plies to get a feel for stiffness as ply material and number can also help carry a small portion of the load (how far do you have to air down an E vice a C load rated tire?). The max rating is a cold DO NOT EXCEED limit to prevent damaging the tire and or hurting people when it goes not a number to set it to for normal use. Higher pressures give less sidewall flex - stiffer ride feeling all the cracks and bumps. The tire will wear the center of the tread first, but give better gas mileage, low pressures will wear the outside first. For your tire I would think a pressure of around 35 would be the high starting point and work your way down (probably end up around 28 - 34 psi for an average off road 33 x 11.5 tire.

BLACKJacK

Your right I didn’t and wasn’t thinking clearly last night. I have been juicing up (coffee) and doing some reading this morning and I understand a little better this morning.

The bicycle analogy helped. Jogged my memory from many years ago. I much prefer my JK today.

Anyway, I will be off to do some testing later today and will report back.

BLACKJacK

Another chalk test today and you guys were absolutely correct that I had the pressure way too high. They were hot when I came up with 36 however plan to try again possibly tomorrow. I am curious to see what the cold pressure is going to be in the morning.

Cheers!

jesse0_0

Hi there, I was wondering about my tire pressure as well lately so I emailed a customer service rep at Toyo Tires..
I'm running 33" Toyo Open Country M/T's

He asked for my stock wheel information on the stickers on the door and information on the 33" Toyo's I had

He came back saying the minimum safety recommended air pressure for my tire is to be set above 37 PSI as to carry the required weight of the vehicle and not exceeding 80 PSI.

He recommends running between 40-50 PSI adjusting for comfort of ride and dependent on the application or driving circumstances

BLACKJacK

After being well educated by others on this forum (thanks guys!) I agree with the chalk test as being the best way to judge the tire pressure. It would be interesting to see what psi yours would be given that information. If you decide to let me know what the results are. Good luck!