Tire Pressure

I checked my tire pressure today for the first time since I bought the Jeep and found the PO had them inflated to 50 PSI! I'm guessing this is too much. What do you guys normally inflate your tires to?

Here is what I have:






On the tire it says "maximum load 2535 lbs at 50 PSI cold". I'm thinking that just because it says that on the tire doesn't necessarily mean that it should be inflated to 50 PSI. Seems too much to me.

 

I went through this a while back while searching for replacement tires on my F150. Basically an LT rated tire will have an higher weight rating than a P rated tire but only at the recommended inflation. If you decide to run the LT tire at a lower than recommended pressure you will actually decrease the vehicles load rating. IMO you probably won't see any difference running the tires at a lower pressure on a CJ5 unless you are going to pull/haul something heavy. I am attaching a PDF written by Yokohama that better explains what I have tried to say. I hope it helps....

 

Tire pressure is based on vehicle weight, not what is printed on the sidewall. That is why you look up tire inflation in the owner's manual of a vehicle (for the OEM tire size).

I've found on intermediates with 33x12.50, 15psi or so works well. Just switched to 33x10.50 BFG on my early and bumped up to 18psi. So, maybe somewhere around 16 or 17 with your 32x11.50?

Draw a line across the tread with a grease pencil and deflate until you get even wear (decrease the crown).

 

The press. on the sidewall for LTs is for airing up to maximum load weight the tire is duty rated for.

 

I agree with jayhawkclint and CJjunk, The tire only needs enough pressure to maintain its design profile under a given load,Chalking works good. Another effective method for determining a baseline pressure to work from with radial tires is to place a square or the corner of a toolbox on the floor about 1/16 inch away from the sidewall bulge with the tire at the maximum rated pressure and the vehicle loaded front and rear to match your daily driving, Deflate until the tire starts to loose its profile and just touches the square. Record your front and rear profile maintaining pressure, This will yield a safe psi for street use that rides good and will give you a good place to start from.

 

X2
this will give you the correct psi for you're specific tire and Jeep setup.

This won't give you the best mpg because more of the tire is touching but will give you the best on road traction and tire wear.

 

So what does the owner's manual recommend?

I know 50 is too high so I dropped mine to 30 until I use the grease pencil method. 18 seems pretty low....

 

You could take your Jeep to a vehicle scale and have it weighed. First do the front end ,then do the rearend. After you know the weight of a particular end divide that number by 2 ( because it was weighed sitting on 2 tires) .Now you know the approximate weight load present on each tire of this particular end of the Jeep. Go online or to a tire store and look up the weight rating of your brand and type of tire and find the pressure rating that most closely matches your application.There are charts that show the weight ratings at various pressures on the tire,not just the maximum laod for that particular tire.. Do the same for the other end of the Jeep. If you want to get real technical you can weigh the four corners individually and also load the vehicle as planned on for the occasion and sit in the drivers seat for the most precise accuracy.I realize that it seems like a lot of work but it would yeild be the most accurate results for your application.

 

I usually run 20 in my 35's and it still beats me to death.

 

On the road I run about 25 psi for a nice smooth ride.
Off road, I like 5 psi!

But I have bias ply tires, and beadlocks, so this info means nothing to you!

 

The tire guy guessed at 25psi for my 31x10.5s and its perfect. Set them at 25 and go from there.