Tires: After market tire inflation, bf goodrich, maximum inflation

Question
I just purchased a 2000 F350 4X4 crewcab w/ 4"? lift. Original size LT265 / 75R 16E, now fitted with BF Goodrich 35 X 12.50R  16.5LT 123  M+S.    How do I figure the correct tire inflation?
Thank you in advance

Answer
Tom,

The first step is to find the vehicle placard and see what it says.  On a Ford it is located on the driver's doorpost near the bottom.  My book says that it should say the original tire was LT265/75R16 LR E inflated to 70 front / 80 rear, but I think the book is wrong for the Ford Super Duty's.

Assuming the book is right, an LT265/75R16 would them have a maximum load carrying capacity of 3105 front and 3415 rear.

To carry the same load, a 35 X 12.50 R 16.5LT has to have...uh....well...uh....  I don't actually have a load table for this size.  I know that the 16.5's are strongly being urged out of the market, and one of the ways they are helping is to remove the listings from the standards books.

Assuming the load table would be the same for any tire with the sae Load Index and same maximum inflation pressure, then the pressure would be 45 psi front / 50 rear.

So the task now is to verify that my book is correct.  If it is not, then the pressures I gave you would also be incorrect.