Tires: Tire upgrade pressure., chevy suburbans, tire guides

Question
'03 Suburban 4X4. Upgraded tires from 265-70-16 to 285/70-17 To gain height and maybe help low gearing/mileage problem. What change in air pressure is needed?

Answer
Jack,

According to Tire Guides, there were several versions of 2003 Chevy Suburbans and one of them came with P265/70R16's inflated to 35 psi.  Please the vehicle placard to make sure this is correct, because what I am about to write depends on this being correct.  (The placard can be found on the driver's doorpost.)

So if the information above is correct, in order to carry the same load as a P265/70R16 does at 35 psi, a P285/70R17 would need to use 26 psi.