Tires: Tire/Rim width, tire placard, chevy 4x4

Question
I currently have a set of P265-75R/16 tires on a 2004 chevy 4x4 pickup. The wheels are stock aluminum. I need to purchase new tires but I don't want the new tires to be as wide as the current tires. I am not going to buy new wheels. What is the narrowest (most narrow) tire I can mount on the existing wheels? 255? 245? etc.
Thanks for your help.

Answer
Jim,

On every vehicle sold in the US, there is a sticker – commonly called the tire placard - that lists the original tire size and the proper pressure for that size.  The placard is usually located on a doorpost or in the glove box – but sometimes it is located in the trunk or on the fuel filler door.

If your placard says the original tires are P265/75R16, then  that is the proper tire size for your vehicle and no tire shop worth going to will but on anything narrower.  That would be going down in load carrying capacity and that increases the risk of a load related tire failure, which sometimes has tragic consequences.