Tire pressures can vary with the temperature.
The temperatures in Iowa have gone up and down by several degrees in the last few weeks and you may’ve noticed the same thing is happening to your tire pressure.
The chair of the Des Moines Area Community College automotive program, Jerry Burns, says the air in your tires reacts to the outside air temperature. “For every ten degrees in temperature change, the tire pressure can change up to one PSI,” he says.
You’ll really notice it on the digital readout of your car if you are in a heated garage and pull out into the cold air. Burns says it’s important to make sure there is enough air in your tires — as the warning alarm usually goes off with a 10 to 15% drop.
“What I typically do during the winter is adjust them slightly higher. So on something that is a 35 PSI tire, I will probably adjust it to somewhere around 37 PSI,” He explains. “Because if you look at it — in order for that light to really come on — I’m going to have to be down around 30 to 32 PSI.”
The recommended tire pressure is listed on the inside of the door and he says it’s important to only adjust the pressure up a few pounds beyond the recommendation. Burns says that will keep the tire from getting too low. “When you run a tire low you put an awful lot of stress on the sidewall of the tire. And you actually start to break down what we call the inner liner of the tire and it actually weakens it from the inside,” according to Burns. “And you can actually do a lot of damage from running on an underinflated tire.”
He says if a tire is overinflated you risk a possible blowout. He says as the tire warms when you go down the road, the PSI will increase some, so that is why he only suggests a few PSI above what the tire placard in your car says.
Burns says tire pressure can also make a difference in the handling of the car. “Having the right tire pressure is going to give you the best contact pattern of your tire on the ground. An underinflated tire is going basically touch on the outer edge — so the inside edge and the outside edge — but the middle is kind of going to go up like a dome,” he says. “Sometimes people think if I let some air out of my tires I am going to get better traction — and that’s not always necessarily the case.”
Burns says some dealerships offer you another option. He says they put nitrogen in tires and it is not as sensitive to changes because nitrogen doesn’t have the moisture in it that air does and the pressure does not change as much. Nitrogen is an added cost.
Burns recommends you make the slight winter change when the temperatures are going to be up and down. He says you should then readjust heading back into spring and summer.