Tire light coming on?

How the TPS (Tire Pressure System) is affected. The tire pressure system is most affected by two anomalies. The first one is temperature and the second one is atmospheric pressure from elevation change or change in low and high pressure. Your tires support the weight of your vehicle, right? Well they don't! It's the air pressure inside them that actually supports the weight. Maintaining sufficient air pressure is required if your tires are to provide all of the handling, traction and durability of which they are capable. Since air is a gas, it expands when heated and contracts when cooled. Since Flagstaff has been having cold days lately it will be affecting your tire pressure more with the fluctuation in the temperature. For every drop in 10 degrees will affect your tire pressure by one PSI. Also having your car sit in the afternoon sun can artificially raise your tire pressure. Having air instead of Nitrogen will also affect how the temperature fluctuation reacts. If the temperature drops 30 degrees overnight like Flagstaff can happen, then it can set off your tire light in the morning. The elevation difference from sea level to Flagstaff’s 7,000 elevation will also affect the tire pressure. However, as altitude increases, atmospheric pressure decreases. For example, atmospheric pressure pushes against the earth at 14.7 pounds per square inch (1 kilogram per square centimeter) at sea level, yet drops to only 10.1 pounds per square inch at 10,000 feet as indicated in the following chart. At sea level the atmospheric is 14.7 lbs per square inch of atmospheric pressure while here in Flagstaff at 7,000. The atmospheric pressure is at 11.3 lbs per square inch of atmospheric pressure. So dropping in temperature and rise in elevation might cause no difference because I guess we can say they would cancel each other out. As soon as the temperature drops at night then it will drop the PSI. With Toyota’s TPS system the tire light will go off in one of many scenarios. One is if a 25% drop or rise in a tire pressure is off from the other 4 tires including the spare. The reason this is in place is because, lets say you run over a foreign object and it becomes lodged in your tire. The one tire will start to lose PSI over time and the tire loses 12 PSI. The other tires are at 32 PSI and the one with a nail is in goes to 20 PSI, then a tire light will come on when you turn on your vehicle in the morning. These are a few things that can affect your tire light. So if you have a tire light on it can be as simple as a low spare tire or it can be low PSI in all your tires.