Or: use a tire gauge.

If you ride high-pressure tires in cold weather, make sure to drop a few PSI in them before you bring them back inside. I blew a tire today - not a tube the actual tire - and it was not a pleasant sound. I mean we're talking bad "bikes may never be allowed in the building ever again" bad

I stole the pressure*Volume = mu(number of moles of gas)*R(Universal gas constant) *Temperature(in Kelvin) from another similar thread, but long story short, bringing a bike in from a 1.5hr commute in 34* temps to a heated building can up the tubes inflation something like 15psi. Again, this is a PSA, particularly useful if you like having a bike anywhere near your workplace. Then again most y'all ride at 70psi and it doesn't matter!