I use chalk to help determine the correct tire pressure, record that psi number and use it to check and set that pressure from then on. I simply scrub the chalk across the tread of the tire in a one inch wide band from side to side on the tread, drive the car forward 40 or 50 feet and see where the chalk has been rubbed off, middle, outside edges or evenly. I adjust the tire pressure to get a full even scrub of the chalk off the tread. That is the tire pressure I need for that tire with that load on it. Period.
I generally run 32 up front and 18 in the rears to get them to the correct shape. Other factors such as spirited driving at higher speeds sometimes force me to increase rear tire pressure a couple of pounds to help stiffen the tire flex out back.
While that method may work on our old cars it sure won't fly on a 2016. 18 psi will certainly flag the TPMS light(and rightly so) TPMS limits are based off what's published on the door tag.
Agreed, and I don't know of any 2016 and up cars come with Nitto Drag Radial 265/60-15's on an 8 inch rim. That's the only reason mine get to the correct shape on the ground with such a low pressure.
The TPMS on my 3/4 ton truck is always as the factory recommends 60 to 80 psi in the rear tires, which is way to high of a pressure when it's empty. Most trucks I see wear out the center of the tire long before the outer edges are worn. I run 42 psi in it after using the same method. Results in nice even wear with the TPMS always on. I'm going to bribe the shop that mounts my next set of tires to program it differently than whats posted on the door sticker to keep the light off.
