How does heat impact tire pressure?

CHICAGO — Summer has officially returned to Chicagoland, and while there is plenty to love about the city’s favorite season, the summer heat could also be a source of headaches, especially for drivers.

For drivers, one of the most noticeable impacts from the heat is tire pressure. Hot pavements warmed by the summer sun could cause increased tire pressure, which could then lead to a host of issues, like premature wear, decreased fuel efficiency or even a blowout.

While tires can naturally lose pressure through permeation, the process where air molecules gradually escape through the rubber, weather has a much bigger impact on pressure fluctuations.

In fact, tiremaker Goodyear says for every 10 degrees of increased temperature, tires can increase by as much as 1 to 2 pounds of pressure. Cold weather can also cause tire pressure to fall at a similar rate.

Overinflated tires may cause your car to bounce more than it normally would because less of the tire is in contact with the road.

What to look for:

According to AAA, tires have a significant impact on a vehicle’s handling, ride, braking and safety, and maintaining the proper pressure is vital to avoiding damage and danger.

Tire safety in the summer months begins with regular checks of a vehicle’s tire pressure.

Checking pressure:

AAA recommends drivers always check their vehicle’s tire pressure after the car has been resting.

To check the pressure of a tire, drivers will need to use a tire gauge, which measures a tire’s air pressure in pounds per square inch (PSI).

Gauges come in three types: stick pressure gauges, dial pressure gauges, and digital pressure gauges.

All three types perform the same task, but digital gauges are known to be more accurate and easier to read.

While AAA recommends drivers check their tire pressure around once a month, many cars nowadays are equipped with a tire pressure monitoring system (TPMS) which automatically measures pressure and notifies drivers of any changes.

When to take a reading:

AAA recommends drivers take a reading of their tire pressure if they notice a substantial shift in temperature, decreased gas mileage, sluggish response times, or if the TPMS indicator light on the dashboard comes on.

Readings that are taken right after a drive could be inaccurate due to heat buildup, expansion and pressure increases.

In order to get the most accurate reading during the summer, drivers are advised to let their car rest for at least four hours after a drive before taking a reading.

The ideal time to take a tire pressure reading is first thing in the morning, AAA said.

Over-inflation or Under-inflation:

While a tire gauge should be used to determine the proper PSI, there are some signs that drivers may notice that could indicate improper inflation.

According to AAA, too much air will cause a tire’s middle section to contact the road more than the rest of the tire, which creates wear primarily in the center of the tread, with less wear at the edges.

On the other end, an underinflated tire will cause the tire’s outer edges to disproportionately come into contact with the road, which will result in wear to both edges of the tire tread.

Drivers dealing with improperly inflated tires may notice their vehicle pulling to the side of the impacted tire.

Overinflating could also cause the car to bounce more than usual, because less of the tire is coming into contact with the road.

No gauge readings:

Drivers who do not have a tire gauge can get a general idea of the state of their tires, though a gauge is required to find the true PSI.

Without a gauge, AAA says drivers can simply look at their tires to look for any center wheel or outer wheel damage, as tires will wear prematurely if improperly inflated.

Drivers can also feel the tires. If they are soft to the press, then it likely has low pressure.

Look for handling changes, as an improperly inflated tire could lead to a bumpier than usual ride or steering difficulties.

Adjusting tire pressure:

If tires are over the recommended PSI, adjusting the pressure is not difficult.

Just like when filling a tire, to decrease the pressure, remove the valve stem cap, depress the center valve pin with a tool, tire gauge or fingernail, and pause frequently to check the pressure.

AAA advises drivers to ignore the number on the sidewall of their tires, and instead refer to the vehicle manufacturer’s recommended pressure.

Usually, the manufacturer’s recommendation can be found in the vehicle owner’s manual or on the sticker of the driver’s side door jamb.