Q: I enjoyed your recent article on tire technology improvements and the demise of the full-sized spare. One area where technology appears to still need improvement is in recapping of tires. This observation is based on the amount of tire-tread debris on roadways, particularly on interstate highways. It is not uncommon to have to swerve around sections of tire tread on the roadway. I have had at least one instance where we were nearly struck by tread from the truck ahead of us while traveling at highway speeds. It would be interesting to learn how often accidents have been attributed to retreaded tire sections coming off of trucks and what process improvements have been made in recent years. As I understand it, retreaded tires are seldom used any longer on passenger vehicles, but they are common on truck tires for cost reasons.

— Dean Nelson, Upper Saucon Township

A: The retread-tire industry insists that the product is as safe as new tires, Dean. And the safety studies I've found appear to back up the claim.

You're right, retreads were a fairly common option for passenger-car tire replacements years ago, particularly for budget-minded motorists. That was the case in the early days of the Warrior's driving experience in the late 1960s and into '70s. Retreads or "recaps" have all but disappeared from the passenger-vehicle market since then.

Jeff Yurasits of Joe's Battery & Tire in Allentown, a 29-year veteran of the business, said Joe's probably hasn't sold a retreaded passenger tire in the last 10 or 15 years. "They pretty much were priced out of the market," he said, as new-tire prices declined, narrowing the price differential. Low-cost new tires from overseas were a factor in that process, according to the retread tire industry.

Today, "You can get a brand-new tire for a little bit more than a recap," Yurasits said. "You get a better quality tire … you don't have to worry about the tire coming apart."

But they don't come apart any more easily than new tires, according to the Tire Retread & Repair Information Bureau, which represents the retread industry. That's a mistaken belief that might linger from experience with a limited number of post-war retreads that weren't up to snuff even for their time, according to retread bureau Executive Director David Stevens.

"It's always been a public perception problem," Stevens said. According to the industry, it's not the manufacturing process that needs improvement, but our perception of the tires' safety and durability.

It's not just the retread bureau, which has an interest in promoting retreads, that contends they're as safe and reliable as new tires. An official at Goodyear agreed when I discussed the matter a few years ago, and the Pennsylvania Motor Trucking Association also stands by the safety and reliability of retreads.

The most comprehensive independent study I could find, commissioned by the National Highway Transportation Safety Administration, is a bit dated, from 2008, but it's pretty convincing. It found that the proportion of tire debris from retreads compared with new tires "is similar to the estimated proportion of retread and [new] tires in service. There was no evidence to suggest that the proportion of tire fragments/shreds from retread tires was overrepresented in the debris items collected."

As for highway safety specifically, "The evaluation of available crash data shows that vehicle crashes related to truck-tire failure and truck-tire debris are very rare events that account for less than 1 percent" of traffic accidents, the study concluded.

Though they've hit some potholes in the passenger-car market, retreads are standard models in the trucking industry, and, for further proof of their reliability, in the airline business. Retreads routinely bear the weight and gargantuan force of today's wide-body commercial jets at touchdown, according to the retread bureau, which reports that retreads account for 80 percent of aircraft tires in service.

But if retreads are so good, and they're pretty much limited to tractor-trailers these days, why do we see pieces of shredded tractor-trailer tire on the roads almost exclusively? If the federal study is any indication, many of these "gators" are pieces of brand-new tire; the expected proportion of the two tire types was found in the samples collected.

Big-rigs travel longer distances over sustained periods of time compared with the trips taken by us regular warriors, and that stresses all tires, new or retread, according to the retread bureau. Truck drivers have many more tires to check, and improper maintenance — underinflation is a big culprit, as it is with passenger tires — can lead to failure, Stevens said.

In addition to the narrowed price differential (caused in part by the advent of low-cost imports of new tires), the multitude of passenger-tire sizes made it difficult for retreaders to keep pace, Stevens said. Truck-tire sizes vary far less.

The tire industry boasts an 80 percent recycling rate, and a lot of that is attributed to retreading. We'll turn to some of the other reuses, including adding old tires to asphalt for road paving, in a future column. But clearly, retreading saves oil, rubber, and energy. It takes about a third as much oil to make a retread as a new tire, according to the retread bureau. A new truck tire, for example, requires 22 gallons to produce, while retreading that tire uses about seven gallons.

About 730 retreading plants are operating in the U.S., Stevens said, representing a $3 billion business and employing thousands of people. It's great that the tire industry recycles 80 percent of its products, but with about 300 million tires discarded each year, that leaves 60 million unaccounted for, mostly ending up in landfills or tire piles where smoky fires are a threat.

Stevens said he doesn't anticipate the passenger-tire retreading business turning back onto Main Street in America any time soon — it still survives in other parts of the world — but maybe it should. I'd consider retreads if I were convinced they're as safe and durable as new tires, and the evidence supports those notions. They wouldn't necessarily have to be cheaper; the same price would suffice. The savings would be environmental.

How good would it be if we could cut back to "only" 30 million tossed-away tires every year?

Road Warrior appears Mondays and Fridays, and the Warrior blogs at mcall.com. Email questions about roadways, traffic and transportation, with your name and the municipality where you live, to hartzell@mcall.com, or write to Road Warrior, Box 1260, Allentown, PA 18105-1260.