Load Range E tire pressure: how do you keep them up?

Your tire pressure will change 1-2 lbs for every 10 degrees of temp change. Check them when it is 40 degrees in the morning and then check them after the sun shines on them and it get up to 80 degrees in the afternoon just to prove it to yourself. This is why they have you check pressures when the tires are cold. If you inflate them when they are at their coldest state for the day they will never be under-inflated.