FYI: How to Check Your Tire Pressure

[srbeards]

This discussion is very interesting but brings up a couple of questions in my mind, assuming tire pressure is really this critical

Since the recommended pressures seem to be tire size and manufacturer specific for the vehicle loading. How does one decided where to set the normal pressures when changing to a different tire size or manufacturer?

The second question is, should I just trust the accuracy of the TPMS system readings when I decide what pressure to use? I don't have my new Ranger yet but a couple of days ago, I was adjusting pressures on my other vehicles with my Viair 400P. I tried several gages including the Viair and the various gage readings differ by about 5 PSI. Using the Viair gage to set my Malibu tires, the TPMS gave me three different numbers among the four tires and they varied about 4 PSI highest to lowest. Which one to believe?

I worked in quality assurance for a long time and always had to be aware of accuracy and repeatability of various measuring instruments. Seemingly simple things can actually be pretty complicated sometimes. Maybe there's a tire pressure setting course somewhere that I can attend that takes this all into account. LOL

I am not a tire expert, but I do switch between three sets to tires/wheels on my Golf R (Snow, Summer and Track). From all the reading I have done, the load rating compared to your door card recommend PSI is what determines what PSI you should run if you change tires and load ratings.

This chart has been helpful for me.

http://static1.1.sqspcdn.com/static/f/589830/23447320/1378330097907/Discount+Tire+inflation.pdf

For example:

My car came with 235/35R-19 tires with a 91XL Load Rating and the door car recommends 39 PSI. My snow tires are 225/45R-17 tires with a 94XL Load Rating. I put 35 PSI in them as recommended by the chart.

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[Secousse]

This chart has been helpful for me.

http://static1.1.sqspcdn.com/static/f/589830/23447320/1378330097907/Discount+Tire+inflation.pdf

Seems that this link is dead