Cold weather is upon us in the Northern half of the United States, and we’re just over a month away from the official start of Winter. For many of us, that means freezing cold temperatures, but that also means “winterizing” our vehicles. While making preparations for the cold weather, we sometimes forget to check some of the more basic things, like tire pressure. Here’s why it’s important.
Tire pressure loss over time and temperature.
There are two important things to keep in mind about tire pressure. Let’s assume for simplicity that your recommended tire pressure is 32PSI.
- Tires lose on average 1PSI of air every month. If the last time you checked was 3 months ago, you’ll have lost ~3PSI and you’d now be at 29PSI. Make sure to check your tire pressure at least every 3-4 months.
- Tires lose on average 1PSI for every 10 degree drop in temperature. If the outside temperature was 85 degrees 3 months ago and is 45 degrees today, you’ll have lost another ~4 psi and would be down to 25PSI.
Reasons to check tire pressure:
Remember, a drop in tire pressure increases rolling resistance, increases friction, and reduces sidewall rigidity. The results of this are:
- A reduction in your fuel economy.
- An increase in the heat produced by the friction in the tires sidewall. Because it now flexes more per revolution than it did before, this heat accelerates the irreversible degradation of the rubber compound in the tire and increases the chance of a blowout in the future.
- A compromise in handling and stability. The “spongy” feel of an under-inflated tire may improve ride quality, but it will not feel as confident and sure-footed in the event that an evasive maneuver needs to be executed, leading to a possible loss of control.
A few things to keep in mind when checking your tire pressure:
- Use a quality tire pressure gauge. Even some of the cheaper dial gauges I’ve used in the past have been off as much as 4psi. Don’t use the tire gauge attached to the air pump at a gas station, as they are often poorly calibrated and not accurate.
- Check tire pressure when the tire is “cold.” That is, wait at least an hour after you have driven the car before checking the pressure. Your tire pressure fluctuates due to the heat created by the sidewall as much as 5PSI between its cruising temperature and its “cold” temperature.
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