The pressure’s on for tire safety

With record-breaking heat waves scorching up cities around the U.S., it’s never too late to make sure your tires don’t fail and leave you stranded on an important trip. Heat is the biggest natural enemy of a tire (not counting curbs and poles as “natural” enemies).

Remember that when the temperature increases, so should your attention to your tires.

What causes tire failure?

Most tire failures are caused by underinflation. Especially when the temperatures are high, underinflation can make the tire run hotter than it should. The underinflation will also allow the tire to flex beyond its design, which can cause the tire to fail.

If the tire is not correctly inflated, it may not be able to stay cool enough to stay together. Another problem is that the tire will not be making correct contact with the roadway, generating excessive heat in specific areas of the tire (normally the “shoulder” or “edge” of the tire).

Types of tire underinflation failure

Any tire that is well below rated pressure (less than 80 percent) is prone to complete catastrophic failure. This is because the extra heat being generated is not getting absorbed by the air inside the tire, causing the tire to chemically break down. This chemical breakdown is what causes the tire to fail catastrophically.

Underinflation may also cause a “zipper” failure. While not as spectacular as a catastrophic failure, the results are the same: The vehicle is stuck with a flat tire.

Zipper failures happen because a tire that’s underinflated can’t hold the correct shape as it turns. The tire sidewall will bend more when it contacts the roadway and straighten more when it comes off the road. The effect is the same as bending a metal coat hanger back and forth repeatedly. In this type of failure, the sidewall “zippers open” because of the extra flexing, hence the nickname.

Check your tires

To prevent underinflated tire failure, complete pretrip, enroute, and post-trip inspections that include checking the inflation and condition of the tires. These inspections are critical during the summer. Every driver should know:

• How to gauge tires while they are cold using an accurate tire pressure gauge.
• To avoid gauging at hot tire that will lead to inaccurate results.
• How to “thump” tires during enroute inspections to check inflation.
• How to check for excessive heat.
• The correct pressure at which to refill or get tires filled.
• How to refill tires safely.
• Which pressure requires a trip to the repair facility instead of a self-fill.

Underinflated = unprepared