I am running 315/70/17 Pro-Comp Extreme M/T's on 17x9 Pro-Comp 7189 Wheels. I was wondering if anyone is running this set up or close to it, If so what Tire PSI are you running for daily driving? Any input would be appreciated...

C:\Documents and Settings\Marc.catalina\My Documents\Cassidy\Cassidy 527.jpg

 

Look here:

https://www.jk-forum.com/forums/show...ighlight=chalk

 

I am running 26 psi with my Xtreme Mud terrians on a 8" rim.

 

Thanks. These things are at 42psi. No wonder I am bouncing around so much. Time for the chaulk test.

 

Before you go and do the chalk test think about it for a minute. The tire is part of the suspension. Your Jeep has been engineered and tested to perform at its optimal levels with the tires at 35 psi. While a chalk testonly proves you full foot print at lower pressures, it does NOT prove anything else. Anyone who watches NASCAR knows that a differance of ony 1/4 pound makes the difference between turning and not turning. While this is an extreme example, I think you get the point. Lowereing your tire pressure below 35 psi will give a softer ride because it ultimately lowers your spring rate. Lower spring rate means more body roll in corners, more body roll means ESP involvment while drivng everyday. Remember a few years ago in So Cal. ALL the tire failures?? LOW TIRE PRESSURE was the cause of 99% of those accidents. So just keep them at 35 psi. and keep the chalk in the classroom where it belongs.

 

The Jeep was engineering and tested using tires of all different sorts, with different sidewall strengths and load ratings at different air pressures. So from a spring rate perspective, you'd have to know an awful lot about the tires you're buying to know if they will perform the same as the stock tires you're replacing, as well as exactly what the spring rate of your lift springs is compared to the stock springs you removed. So just ignore all that

Doing the chalk test is a good idea to try and maximize tire life. Anything over 30PSI is pretty road-safe.

-E