What tire pressure to run?

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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.
 
Thanks for the help everyone!
@Capriracer, I'm running 8" wide rims now, how does that effect pressure? (vs 7 stock)
 
Originally Posted By: HoosierJeeper
Thanks for the help everyone!
@Capriracer, I'm running 8" wide rims now, how does that effect pressure? (vs 7 stock)


From a load carrying capacity point of view, it doesn't.
 
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