Air pressure variances

[talnlnky]

So... took the yaris in to redeem one of my free oil changes (not too much a fan of castrol syntec which I tried the past 5k). Had them rotate the tires (was free) and they commented that my tires were at 49psi. Now... I know its easy to get messed up readings on guages easily. But last time I touched the tires they showed 44ish +/- 1psi. I cited that I ran them around 44, and that it must be the warm weather (bout 30-40F higher) and the dude said that'd only make 1-2psi Difference.

Is he right? does ambient temp barely make a difference?
For the record... i'll be pumping my tires back up to 45 after a few days of sitting at 40psi (which they dropped it down to). They tried to convince me to put them back at 32, but I think they & I didn't want to argue, and I sure don't want them noting that I'm going above spec in their computers, so i didn't argue.

Noise does seem to be lower at 40 which I do like. Makes me wonder how quiet my car would be if I dropped back down to 32 like I ran for the first year of its life.