Why do radial tires fail when overloaded or underinflated?

I have a number of posts here on RVtravel.com on the topic of why tires fail. There are also more than 16 posts on my Blog RVTireSafty.net that mention “separation” as a reason or contributor to a tire failing. But maybe some want more a scientific explanation.

The above graphic is a computer-generated color depiction of the relative heat generated internally to a tire as it is driven down the road. Light blue is the coolest area, and red is the hottest.

When tires crack

I have covered the “artificial aging” of rubber in a number of posts. Basically, the molecular cross-link density increases, which can be thought of as stiffening and less flexibility. When rubber loses its flexibility, the molecular bonds crack. As more bonds crack, these cracks join up until they can be seen with the naked eye, as pointed out with the yellow arrows in the picture below.

When tires develop these larger cracks, they simply grow over the next hundreds or thousands of miles, as seen in the next picture.

“Free-Spin Inspection”

Tires with these larger cracks can be identified by doing a “Free-Spin Inspection,” as covered in detail in my post on my blog on how I inspect my tires.

When doing a “Free-Spin Inspection”, If you discover the out-of-round or side-to-side movement as seen in the video in the above post, I strongly suggest you have the tire inspected by your tire dealer for that brand tire, or simply replace the tire if it is more than 3 years old.

By the way, the steel belts do not “slip”. They are no longer attached as part of the structure of a radial tire.

Roger Marble

MORE ON RV TIRE FAILURE

• Do you think tires ‘magically’ fail? Here are some facts
• How to avoid tire failure
• What to do after an RV tire fails; how to make tires last longer
• What to do if you have a travel trailer tire failure

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If you have tire questions, check out Roger’s Blog as well as his posts on RVtravel.com. There are hundreds of posts covering everything to do with tires.

If you still have a question for Roger after searching the above posts, send your inquiries to him using the form below.

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