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How Temperature Contributes to Tire Pressure
If you paid attention during physics class, you'd know that the pressure and volume of a gas in a closed system may only remain constant for as long as its temperature remains constant. This is an important point to keep in mind since a car's tire is a closed system filled with gas. This also means that the tire's inflation pressure will react according to the rise or fall in the operating temperature.
As a rule of thumb, for car tires, you can expect to see a pressure change of one pound per square inch with each 10 °F change in the temperature of the air chamber in the tire.
Cold Tire Pressure vs. Warm
Contrary to popular belief, filling air in the tires of your car is not as straightforward as one might think. For instance, when the temperature is cold, the air in the tires takes up less volume than when the temperature is high, where car tires tend to take up more volume. This change in the volume pressure is why car owners need to educate themselves on cold tire pressure vs warm tire pressure.
Getting familiar with the tire pressure and cold tire pressure vs warm tire pressure is crucial to ensure that the tire pressure is always at an optimal level, regardless of the weather. It is also important to note that the inflation pressure of a car tire tends to drop as the temperature lowers. For instance, it is normal for car owners to see tire pressure dropping by 1 or 2 PSI per 10 degrees drop in temperature.
This works both ways. For example, car owners often notice an increase in the pressure in their car tires for every five-minute interval of the first 20 minutes of driving. This increase in the tire pressure of about 1 PSI is because the car's tires normally start to warm up after 20 minutes of driving. This is also one of the reasons why car manufacturers recommend specific PSI for optimal tire performance, depending on whether the car tires are warm or cold.
Hot vs Cold Tires: What's the Difference?
Tire manufacturers recommend the ideal PSI for specific tires, which dictates the optimal level for your car and the tires. However, it is important to note that these recommendations by tire manufacturers are normally for cold tires, where the air takes up less volume. This is also why once the temperature drops during the winter season, the in-built computer system in most modern cars indicates a low pressure in the tires.
In an ideal situation, when filling air into the car tires during the winter season, car owners should wait for the time when the car tires are cool, as in, in the morning or late in the evening, when the car has not been driven for at least a few hours.
Sadly, since there's no way of inflating the tires of your car at home, most people have no choice but to drive their car to the nearest gas station, which can heat up the tires. To be sure your tires always have the right amount of pressure, measure the PSI of your tires before you leave home. Then measure the PSI of the tires again once you reach the gas station and just add the PSI you need according to the first PSI reading.
Underinflated/Overinflated Car Tires
It goes without saying that there may be some serious consequences if the tire pressure is not accurate in a car. For instance, leaving the car tires underinflated can lower the amount of control one has on the steering, making it more difficult to maneuver while driving. It can also lead to quicker wear and tear of the car tires, which will require you to change the tires sooner. More importantly, though, under-inflated car tires are one of the main reasons for the low fuel efficiency of most cars.
On the other hand, overinflating a car's tires can lead to a bumpy and uncomfortable ride, which is why you shouldn't over inflate or under inflate car tires. To make sure that all of your car tires have optimal pressure, it is important to check the tire PSI at least once every month.
This is recommended by mechanics and tire manufacturers mainly because regardless of whether or not there's a leak, car tires will still lose pressure, and there's also a good chance that the computer system in your car will not indicate that slight pressure change in the tires. In short, checking the PSI of your car tires every month ensures better performance while increasing the tires' longevity.
Adjusting Tire Pressure
It is recommended to set the tire pressure to the manufacturer's recommended cold PSI setting if current tire conditions meet the manufacturer's definition of "cold." This pressure is usually listed clearly on the owner's manual or on the tire itself or can be found on the loading information placard that's on the doorjamb.
If you are going to inflate the tires in conditions that aren't cold, then it is recommended to compare the current condition of the tire to the cold condition of the tire. This is done to accommodate the temperature difference of the tire and ensure that the PSI level of the tire is always at an optimal level.
Set pressures 4 PSI above recommended in the morning and 6 PSI if checked and set in the afternoon. This is for when the car tires are warm after the car is driven. Also, it is important to note that you should never bleed hot inflation pressures to less than 6 PSI above the recommended cold pressure if the tires are warm and the tire pressure is high. For vehicles that are parked for long durations, it is advised to set tire pressures to 1 PSI above the placard recommendation. This is to be done for every 10° Fahrenheit temperature difference from indoor (warm) to outdoor (cold) temperatures.
Summer's mild temperatures entice many adventurers to travel along sandy roads, up twisting trails, and across the vast highway system. Warmer weather means exciting road trips with friends and family, but it also means changes in tire pressure in your car. With your knowledge of tire pressure and cold tire pressure vs warm tire pressure, you can avoid the hazards of over- or under-inflated tires and prepare for a safer road trip. You could even improve your vehicle's fuel economy with your newfound tire knowledge!
About The Author
I've spent many years selling cars, working with auto detailers, mechanics, dealership service teams, quoting and researching car insurance, modding my own cars, and much more.Read More About Charles Redding