Here's how to do this:
The principle is to match the original load carrying capacity. The starting point is the vehicle tire placard.
I can't tell which jeep your new tires went on, so I am going to guess the '05. Tire Guides doesn't list the various Jeep models as you've described them in your signature, but I am going to take a guess the pressures listed on the vehicle tire placard are 33/33 and the tire size is P225/75R16. Please check to be sure that is correct.
If that is correct, in order to carry the same load as a P225/75R16 does at 33 psi, a P245/75R16 needs to use 26 psi.
- BUT -
If you can match the load carrying capacity at a lower pressure, it's a good idea to match the original spring rate of the tire, which is mostly about inflation pressure (unless you are changing springs and shocks, too!) - so I would recommend using the originally spec'd 33 psi.
And that would be your new starting point. Some folks like to modify from there to achieve a different goal that the engineers at the factory had in mind.
Oh, and one other point: A P245/75R16 requires a minimum of a 6 1/2" wide rim. I think your Jeep has 7" wide wheels, but you need to check. If you try to use a rim that is too narrow, the vehicle will wander and follow the ruts in the highway, as well as be sensitive to cross winds.
The principle is to match the original load carrying capacity. The starting point is the vehicle tire placard.
I can't tell which jeep your new tires went on, so I am going to guess the '05. Tire Guides doesn't list the various Jeep models as you've described them in your signature, but I am going to take a guess the pressures listed on the vehicle tire placard are 33/33 and the tire size is P225/75R16. Please check to be sure that is correct.
If that is correct, in order to carry the same load as a P225/75R16 does at 33 psi, a P245/75R16 needs to use 26 psi.
- BUT -
If you can match the load carrying capacity at a lower pressure, it's a good idea to match the original spring rate of the tire, which is mostly about inflation pressure (unless you are changing springs and shocks, too!) - so I would recommend using the originally spec'd 33 psi.
And that would be your new starting point. Some folks like to modify from there to achieve a different goal that the engineers at the factory had in mind.
Oh, and one other point: A P245/75R16 requires a minimum of a 6 1/2" wide rim. I think your Jeep has 7" wide wheels, but you need to check. If you try to use a rim that is too narrow, the vehicle will wander and follow the ruts in the highway, as well as be sensitive to cross winds.