I only fill my tires when cold (car has sat overnight), but I do not bother with a gauge. I find it much easier to use the built-in pressure indicator. I use a 12v compressor that connects to the battery terminals. https://smile.amazon.com/Viair-00088-88 ... +00088+88P
I turn the car on, when filling the tires, so the battery doesn't drain too much. When it gets up to the recommended pressure, the car horn honks once. When it hits what the system considers the maximum acceptable pressure, the horn honks three times. I then turn off the compressor and move to the next tire. The gauge on the air compressor shows 42psi when I get the three honks. The ride is a little rough, but seems to be okay with the new Ecopias I put on it a couple months ago.