Tires: Tire pressure for different size tire than original, recommended tire pressure, series tires

Question
Hello and good morning,

I have a question concerning a 1998 Ford F150 XLT 2wd extended cab. It originally came with a set of P235 75/R16 tires but I have since replaced those with LT 245 75/R16. I am wondering if I should still use the original recommended tire pressure (32psi Front 35psi Rear) listed on the driver side door of my truck or a different pressure due to the different type of tire. I believe most LT tires have a recommendation of 45psi Front/60 Rear any thoughts?

Answer
Mike,

First, according to Tire Guides, your truck came with 70 series tires, not 75.  So please check your vehicle tire placard to make sure this is true as what follows is based on what Tire Guides says.

In order to carry the same load as a P235/70R16 does at 32 and 35 psi, an LT245/75R16 needs to use 36 and 39 psi.