How does hot weather affect tire pressure and what should you do about it?

1. Heat decreases tire pressure; add air when tires are hot
2. Heat increases tire pressure; if tires are too hot, let air out to bring them to normal pressure
3. Heat increases tire pressure; do NOT let air out of hot tires because the pressure will drop to unsafe levels when they cool
4. Hot weather has no effect on tire pressure in commercial vehicle tires