Tires: tire pressure, aftermarket rims, stock rims

Question
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Followup To
Question -
I own a 05 GMC 2500hd 4WD, I put on Hercules LT Terra Trac AT 265/75 16 load range E (10 ply) tires.  Wondering what pressure to run in them, front and rear different, or all the same pressure?  also when the truck has no load {regular driving and highway} or when I have a load.  Thank you for your information!
Answer -
Ryan,

There are so many different versions of your truck that I'm going to need some additional information.

What I need is the original tire size and the inflation pressure listed for that size.  All that info is on the placard which is location on the driver's door or doorpost.  Be sure to include the letters as well as the numbers in the tire size.  They are important!          The original tire size was 245/75 R16 load range E, saying 60 psi in the front and 80 in the rear. hopes this helps a little more. Thanks

Answer
Ryan,

First the stock rims are too narrow for your tires (LT265/75R16), So I hope you have aftermarket rims of at least 7" width.  If you are using the stock rims, the tires are going to be "arched" and try to ride on the center of the tread.  Aside from the wear problems,  You might experience some unusual handling issues - a bit of directional vagueness, sensitivity to wind, or some funny feel when turning a corner.

If you have the aftermarket rims, you ought to maintain the same load capacity as the original tires and the same pressure split - front to rear to maontain the handling (oversteer / understeer). For that you would need 50 / 70 psi.


I do not recommend using different inflation pressures when the vehicle is empty for 2 reasons:  First, the vehicle's shocks, springs, and sway bars were carefully selected for both the loaded and empty conditions at the pressure specified, so the vehicle will handle in a predictable way.  

Second, it is pretty common for folks to forget they have to increase the inflation pressure when carrying a load, so the tires are underinflated and that could lead to a tire failure - and those can sometimes have tragic results.

Hope this helps.