Why Tire Pressure Drops in Cold Weather and Rises in Hot Weather?
While tire pressure drops can be a pain to deal with they aren’t uncommon. This is especially true in climates with big temperature changes.
For instance, those who live in Michigan deal with the drops in tire pressure every fall and experience an increase in tire pressure in the spring.
To better understand this phenomenon we will need to get slightly scientific.
According to the Charle’s Law, when the pressure is constant the temperature and volume must be proportional. This is obviously true with the tire pressure in tires.
The pressure within a tire will remain constant unless you have a leak, in which you will eventually have a flat tire. With the pressure remaining constant this means that the pressure will adjust to the current temperature at that time.
For example, if a tire is at 35 Pounds per Square Inch (PSI) at 70 degrees then when the temperature drops to 30 degrees the tire pressure will be about 31 PSI. While there are much more complex formulas to calculate a more accurate result this change in pressure can be roughly calculated with the following formula:
(New Temperature – Existing Temperature) / 10 = Change in PSI
(30 degrees – 70 degrees) / 10 = -4 which means the tire will lose roughly 4 PSI resulting in 31 PSI from 35 PSI.
If the temperature rises it can be calculated the same way.
(70 degrees – 30 degrees)/10=4 which means the tire will rise roughly 4 PSI resulting in 35 PSI from 31. PSI
The Effects of Different Pressures on Tires (Plus Remedies)
Now that we have a better understanding of how our tires pressure is going to react with respect to the temperature it is also good to understand the effects of PSI on tires.
If your tires aren’t running at an optimal pressure then the tires are pulling money out of your pocket faster than they should and / or could be a safety issue.
What if my tire pressure is too high?
If your tire pressure is too high then most the tire is most likely not going to be performing as it should. When there is too much pressure in the tire it will cause the tire to lose the contact surface area.
This isn’t a good thing as it means more of the weight is transferred to the center of the tread on the tire. This also means that the tire will wear down faster than it should, which will also end up costing you money due to needing to replace them sooner.
Another reason why you don’t want to let your tire pressure get to high is because you will also lose traction. This will also increase your stopping distance which could put your safety at greater risk.
The driver will also feel more of the bumps in the road as the tire won’t be able to absorb them as much due to being so stiff.
What if my tire pressure is too low?
Low pressure in a tire can have a few different effects that can also be costly and unsafe. One of the main reasons tires blow is due to under inflated tires.
This usually happens as the sidewall of the tires have to flex more than they should and they begin to fail over time, mainly due to generating heat while continuously flexing where they aren’t designed to.
Another reason to make sure your tire pressure isn’t low is the life of the tire itself. If the tire doesn’t have the proper amount of pressure then you are also burning tread off of it. This will end up costing the owner more money due to needing new tires sooner as the lifespan of the tire is decreased.
Not only will the lifespan of the tire reduce, but if the tire pressure is too low it can also cost you at the pump. With the tires wearing and tearing more your fuel efficiency will decrease which will in return cost you more in gas.
Since we are mentioning wear and shortening the lifespan of the tires we should make one other side note here as well. Rotating the tires regularly will help the lifespan of the tire.
It is recommended to do this every 7,000 to 10,000 miles and in doing so follow the manufacturers suggested rotation pattern.
What Does the Tire Pressure Monitoring System (TPMS) Light Mean?
The Tire Pressure Monitoring System (TPMS) light is a warning light that your tire pressure is low. The standard says that if your TPMS light is on then your tire pressure is at least 25% below the optimal pressure the tire should be at.
This should be resolved sooner than later to prevent a blowout, wear and tear on the tire & reduce any safety issues from happening.
The tire pressure monitoring system monitors the pressure inside of all four tires. This is done with wireless sensors. The wireless tire pressure monitoring sensor is located in the tire pressure valve.
The stem in the valve acts as an antenna to communicate the readings back to the monitoring system which is located in the dash of the car.
How to Check and Maintain the Proper Tire Pressure on Your Car?
First off, most cars tire pressure should be right around 35 PSI. To confirm always check the sidewall of the tire itself. The side wall of the tire should read something like “Max. Press. 280 kPa (41 PSI)”. If this is the case it is recommended to keep it in the 35 PSI range.
On most newer cars, checking this can be done directly on the dash without even touching the tire. If you have an older car you can purchase a tire pressure reader from any gas station.
Simply unscrew the cap on the tire, push the reader on the tires stem valve and confirm the tire is in the proper range.
If the tire isn’t in the proper range take a compressor and fill it back up until it is. If you don’t have a compressor simply stop at a gas station as most have coin operated tire fill stations.
Why Not Max My Tire Pressure Out?
If you aren’t taking on an extra load on then maximizing your tire pressure is putting it back into the over pressurized tire pressure state. This will have the same ramifications as mentioned above in “What if my tire pressure is too high?”.
So why? Many people do this when they are hauling things. This can be anything from an SUV hauling a trailer or a truck hauling a 5th wheel camper.
What happens is that the load from something like a 5th wheel is putting extra weight directly on the axle, which is then transferred to the tires making them squat. The squatty tires are then basically under pressurized tires and have the same ramifications as discussed above for “What if my tire pressure is too low?”
I have a bachelor’s degree in construction engineering. When I’m not constructing or remodeling X-Ray Rooms, Cardiovascular Labs, and Pharmacies…I’m at home with my wife, two daughters and a dog. Outside of family, I love grilling and barbequing on my Big Green Egg and working on projects around the house.