Safety Dance: Tiremaker Comes at Tread Depth Debate from Odd Angle - Tire Review Magazine

Safety Dance: Tiremaker Comes at Tread Depth Debate from Odd Angle

Michelin broke the tiremaker cone-of-silence in the debate over changing – or not changing, in this case – our scatter-shot tread depth limit regs.

At a media briefing earlier this year, Michelin said change is not necessary, there’s no need for a national mandate, and, even then, lack of enforcement would render such regs moot.

Backed by stats and test results, Michelin took a reasoned approach to its case. But then things took an unexpected turn when it suggested that taking tires out of service at 4/32nds instead of 2/32nds would harm the environment.

 Odd position for a company built on the one word no tiremaker dare utter: Safety. So you can catch your breath, I’ll get to that in a minute.

We all know that one can find stats to support any argument. In fairness, I do the same. And I can’t dispute Michelin’s figures, I can only add my comments and counter-stats.

For example, Michelin quoted a NHTSA study that said that only 1.1% of fatal crashes indicate tires as a factor – but not necessarily worn out tires. The take away, obviously, is that no one can absolutely define how many have been killed or injured in low tread-related accidents.

While I couldn’t find that 1.1% figure anywhere on its online database, NHTSA’s FARS (Fatal Accident Reporting System) doesn’t address mechanical issues, like tire condition. FARS reports are built from accident reports by local police, who don’t always fully determine the causal factors contributing to the more than 10 million traffic accidents that occur in the U.S. annually. Notations of “worn tires” or “tire failure” may show up on police reports, but that’s as specific as it gets.

FARS does say that in 2006 there were 38,588 fatalities in passenger vehicle accidents in the U.S. (excluding pedestrians and two-wheelers). So if one accepted that 1.1% figure, it still means that 424 people died in tire-related traffic accidents.

And since we are talking about a regulatory solution to consumer neglect, remember that the TREAD Act was propagated on 271 deaths allegedly caused by allegedly defective tires.
Consider, too, that NHTSA claims its TPMS regs, once fully implemented, will save some 130 lives per year. “Fully implemented” means every passenger vehicle on the road, which, in real terms, means about 20 years.

Another NHTSA study Michelin cited claims that 9% of cars on the road have at least one tire with insufficient tread depth – below 2/32nds being “insufficient.” That 9% represents 21 million vehicles. Add Canada, and you’re talking about almost 23 million vehicles. So anywhere between 21 and 92 million tires on the road right now have treads worn to the bars!

As Michelin rightfully stated, multiple parties have a stake in treadwear-related road safety: tiremakers, governments, the weather and, of course, drivers. And Michelin noted that enforcement of current state-by-state regulations (only 37 states and D.C. have any regs) is pretty lame. Couldn’t agree more.

Drivers should be held accountable; they’re putting themselves and others at risk. And it doesn’t help to have a law if there is no enforcement. But current lack of enforcement is no reason to not have better laws and safer roadways.

A German study, said Michelin, showed a negligible traction difference between 2/32nds and 4/32nds on “damp/wet” roads and dry surfaces. But that study only measured the front tires. Even then, Michelin said braking distance differences are not a good indicator of accident frequency.

Can’t disagree there. Just because it takes, say, four additional car lengths to stop with 2/32nds of tread than if there were 4/32nds doesn’t necessarily mean that vehicle would be in an accident (though, quite obviously, it does increase the odds). Equally, one could say that braking distance differences between tire brands is also not an indicator of “safety” or of any ability to avoid collisions, injury or death.

Before we move on, let’s consider some other stats, some I have a little more faith in.

In 2007 testing by the Tire Rack, a late-model pickup truck riding on tires with 2/32nds of tread averaged 499.5 feet to stop from 70 miles per hour on wet pavement – equal to about 12.5 school buses or nearly a tenth of a mile. That same truck on tires with 4/32nds of tread stopped almost 122 feet (24%) shorter.

Independent research in 2006 by William Blythe Inc. said that tires with less than 4/32nds of tread may lose some 50% of available friction – even before hydroplaning occurs.

Continental, which advocates a switch to 4/32nds minimum tread depth, has some live track testing to support its position:

• Between full depth and 4/32nds, Conti said, a tire loses 30% of its “safety potential” (traction), but between 4/32nds and 2/32nds a tire loses another 25% of its safety potential.

• From 100 kph, a tire with 5/32nds tread suffers a braking distance increase of 14% vs. an 8/32nds original tread. At 4/32nds braking distance jumps 28% – about 1.5 car lengths. At 2/32nds, braking distances increase 67%, about four car lengths.

Like I said, stats are stats. You should take all of the information out there and determine for yourself which way this should go.

All I ask is that we leave the 4/32nds vs. 2/32nds argument to testing and statistics. Let’s not play the Green card when we’re talking about human lives.

In its presentation, Michelin claimed taking tires out of service at 4/32nds would require 28% more replacement tires each year – 64 million more units – and that a like amount would have to be disposed of each year.

Plus, tires with low tread deliver greater fuel efficiency, Michelin said. Pulling tires at 4/32nds would increase rolling resistance by 2.7%. Through some mathematical formula that escapes me, that 2.7% translated into 750 million additional gallons of gas burned, putting an added 7.5 million tons of CO2 into the atmosphere.

I’m not sure where any of those figures came from, but let me ask:

• How many scrap tires is Gatlin Brown’s life worth?

• How many barrels of oil is Jenny Sue Maurer’s life worth?

• How many pounds of CO2 is Travis Williamson’s life worth?

All were killed in documented low tread accidents, which might have been avoided if their tires were retired a couple of 32nds earlier.

Will a national law or even a passive state-by-state approach save every life? No, but neither will the TREAD Act, TPMS regs, run-flat tires or any number of other “safety” efforts.

The point is not the statistical validity of one path or another. This is all about common sense, about taking a safety stance instead of waiting for the government to act.

Some of you out there get it. I hear from you often, and many dealers have taken the 4/32nds message directly to their customers – with positive results. Sadly, tiremakers – the real stakeholders in this 2 vs. 4 debate – aren’t backing them up. Except for Conti and now Michelin, tire companies have said very, very, very little. And that’s too bad.

To its credit, at least Michelin said something. Maybe that will be the start to some meaningful dialogue. Otherwise, the silence is deafening.

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