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Published on October 9, 2006

Time for new tread depth standard?



AKRON (Oct. 9, 2006) — Tire dealers in the U.S. now have another “hot button” issue to discuss with customers at the service desk.

Recent research in the U.S. and Europe has pointed out the inadequacy of the widely accepted 2/32nds-inch minimum tread depth for tires. This, in turn, has sparked the debate on whether increasing the minimum to 4/32nds is something the industry should pursue to improve vehicle safety.

On the surface, few would argue with the research that shows significantly shorter stopping distances in the wet at 4/32nds tread depth than at 2/32nds.

But the devil's advocate could argue, “Why stop there? If 4/32nds is better, why not go for 5/32nds or 6/32nds?”

For now there is no national U.S. standard for minimum tread depth—the individual states regulate this—although federal law does stipulate that all consumer tires sold in the U.S. be built with wear bars set at 2/32nds.

So how did 2/32nds become the de facto standard?

It appears to have come from warranty coverage parameters during the bias-ply tire era and carried forward since then—despite the wholesale change to radial tires and the market evolution to wider and lower profile tires.

Whether the industry, safety advocates or government takes up this issue, it likely won't be a quick or straight-forward pro-cess.

Consumer advocates might argue the change is an industry ploy to sell more tires.

Environmental types would argue the change will increase the number of scrap tires and put more rubber per tire into the waste stream.

Still others might argue the construction industry should build better roads, with better water evacuation and grippier asphalt.

Would 4/32nds become a national standard? And if so, who would enforce it?

The bottom line for issues like this—as so often is the case—will be financial: How much theoretical tire life will consumers be willing to exchange for fewer accidents, injuries and deaths?

Increasing the minimum tread depth to 4/32nds effectively cuts the tread life of a 50,000-mile tire by as much as 20 percent, or about 10,000 miles. Some would say even more, since tread life per 32nd-inch increases as a tire wears.

With so many questions to address, what should you, as a tire dealer, do about it?

More than three-fourths of you who responded to our online poll at on this subject said you would favor a change to 4/32nds.

Given the growing body of evidence favoring the deeper minimum depth, the question is: Would you voluntarily start advising your customers to change earlier? If so, you should be able to explain why it is important to do so.


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