Fred Jackson san is correct, but here is another way of explaining it:
If you are using a gauge to measure pressure, it is always psig.
However, if you are using one of the gas laws, like the Ideal Gas Law: PV = nRT, both the temperature and pressure are absolute. Put another way, one would have to add 14.7 psi to any gauge measurement and 460° to any Fahrenheit temperature measurement. (273° for Celsius)
Oh, and I only look at this website using the search function: "tire". Your initial post didn't have that. It only showed up today because Fred used the word yesterday.
Also, it is pretty common for folks to use psia (for absolute) and psig when there might be confusion.