testing tyre pressure

wats teh right ambient temp to test tyres?

up here day night temp varies by 20°

and does it matter that much?

I have a servo approx 1km from my house...That is where I go to check the tyre pressure...Usually before the day warms up too much, although, if the bike has been in the shade, I don't think ambient temperature should matter too much

the calibration cerificate that came with my inflator shows -.7 psi @ 40psi

just trying to find out all the variables to make sure its not out any more than that

24.67 Degrees

when the tyres are cold.....