Tires: Tire Pressure, goodyear wrangler rt, goodyear wrangler rt s

Question
I have a '97 GMC Jimmy SLT, 4x4, 4-door. Current tire is Goodyear Wrangler RT/S P235/75R15. My general mechanic says the tires should be running at 45 psi cold. The tire place, after a recent rotation, set the pressure at 32 psi, and the oil change place always runs them to 35 psi. Which pressure is correct?

Answer
Gene,

On every vehicle sold in the US, there is a sticker - commonly called the placard - that will list 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 you are using a different tire size than what is listed, then it can be easily calculated.  However, the calculation requires the use of tire load tables which are not allowed to be published on the internet.  But I have a copy.  If you'll post back with what the vehicle placard says for both size and pressure and the new size on the vehicle, I'll be happy to do the calculation.