Tires: P to LT tires 2003 Suburban, recommended pressure, tire size

Question
QUESTION: I just read an answer you gave last year to someone who had P 265/70-16's put on in place of LT's on her 2003 Suburban.  I am going the other way so as to give a little more stability while towing.  35psi is the recommended pressure for the p tires, 65 for the LT's.  I understand the derating of LT tires but was wondering what a decent average pressure would be for the LT's when not loaded

ANSWER: Dave,

According to Tire Guides, a 2003 Suburban came with either P265/70R16's or P265/70R17's, both inflated to 35 psi.  Please check your vehicle tire placard to make sure that what you have said is indeed the case - because what I am about to write is dependent on that being correct.

In order to make the load carrying capacity of a P265/70r16 at 35 psi, an LT245/75R16 would need to use 50 psi - So you can see why I do not recommend folks switch between the 2.

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QUESTION: I have the 16's and am putting D load LT's of the same size on which I believe have the same load rating as the P's.  I am confused why you reference LT245/75's?

Thnaks, dave

Answer
Dave,

Since you didn't tell me what tire size you were planing to put on your Suburban, I referenced the LT245/75R16 because that is an extremely common size, plus it is the tire size that comes on the heavier duty versions of the Suburban.

But redoing the calculation, in order to carry the same load as a P265/70R16 does at 35 psi, an LT265/70R16 would need to use 46 psi.