I recently spent several days alone with my mother who lives two states away in Pennsylvania.
She's 94 years old, still sharp as a tack and able to get around—albeit slower than she used to. Mom and I spent many hours talking about her childhood, things she remembered growing up and long-gone relatives.
Her birth date is Oct. 10, 1910—that's 10/10/10—which is a pretty cool number. What is most significant is that she has lived through the American Industrial Revolution, the Great War, the Great Depression, World War II, the Cold War, the Baby Boom (for which I thank her), the Sexual Revolution, disco and the end of the Cold War. She survived “Y2K,” the arrival of the New Millennium and the terrorist attacks of 9-11. This woman has seen a lot!
But what does my mom have to do with tires? Everything actually. You see, she's seen the development of retreading over the years. She wasn't around when Dunlop invented the first pneumatic tire in 1888, but she was there to see retreading evolve from its inception.
Birth of retreads
When cars and trucks were first equipped with pneumatic tires in the beginning of the 1900s, the biggest problem was getting the tires to survive cuts, penetrations and blowouts. They only averaged about 1,000 miles before wearing out, but most didn't make it that long since the roads were unpaved and full of hazards.
Even so, people began working on ways to extend tire life. In the 10 years after my mother was born, several ways were invented to retread a tire. One popular method applied several layers of sheeted uncured rubber to the tire. One-third of the tire circumference was vulcanized at a time in a third circle mold. The tire was shifted in the mold until the whole tire was cured.
However, there were problems with this process. Moving the sections around in the mold caused overlapping sections to be cured unequally. Temperature control was difficult, clamps had to be retightened frequently, and molds weren't available for several sizes of tires.
In 1912 Marion Oliver patented a tread design used in precure treads that he cured in 10- and 12-foot lengths and marketed to other retreaders.
In his process, the tire was buffed to the fabric and the precured tread with wings was placed on the buffed tire. A hoop was placed on top of the tread and a spiral spring was put inside the tire to push the casing against the ring. The built tire was coated with talc and soapstone mud then wrapped with strips of cotton. It was cured in a steam-curing pressure chamber and afterwards the baked-on mud was whacked with a pipe to break it loose.
Between 1910 and 1920, transportation really took off in America. The automobile industry in the U.S grew tremendously. While there were only 500,000 cars in 1910, by 1921 there were nearly 8 million.
Interstate trucking began in 1917 when Goodyear's Wingfoot Express made its first run from Akron to Boston hauling tires, of course.
The 1920s roared in with flappers (like my mom) as well as significant innovations for retreading. Extruders were invented that forced pre-heated uncured rubber through a die in a continuous length that could then be applied to a buffed and cemented tire. The full-circle mold also came into being. It included various sizes of aluminum matrices, which made it possible to form fit several sizes of tire.
These matrices primarily were used to cure a top cap to the tire. Air bags also were introduced, placed inside the tires to push the tire against the mold. These replaced the solid iron cores that were used before and really improved the quality of the mold cure retread process.
Buffing equipment also made tremendous advances. Up until this time, buffing was done either by using a hand-held rasp and rotating the tire a section at a time or by using a rasp wheel on a pedestal and placing the tire around the worker's waist. The “buffer” in this case, rotated the tire around his waist a section at a time to buff the entire circumference. (I don't believe this method was approved by OSHA.)
Retreading Equipment Co. in Charlotte, N.C., invented the first “modern” buffing machine. The tire, which was mounted on a rim with an inner tube, was inflated and then revolved against a buffing rasp that provided a uniform buff.
By the time the Great Depression hit, highways as well as tires had improved dramatically. In fact, tires could actually be worn out rather than blowout before their time.
Retreading greatly benefited from these developments in addition to the drop in rubber prices that occurred during the Depression. At this time many small rubber manufacturers were able to sell tread rubber at constantly cheaper prices, which made the cost of retreading very low to tire users and the darlings of the Depression. This couldn't have come at a better time. Retreading was coming into its own.
In 1934 and 1935, 35 major tire companies entered the retreading industry. The cost of a moderate size retread plant ranged between $5,000 and $15,000 depending upon the number of sizes of tires to be retreaded. Paul Hawkinson introduced a ring-type method of curing top caps, which was an economical alternative to purchasing molds as well.
Federal and state governments experimented with retreads on trucks and official cars while private truck and bus fleets as well as individual motorists purchased them. By the end of the decade retreads accounted for 5 percent of the replacement passenger tire market and 20 percent of the replacement truck tire market.
Despite all the country's hardships during the Great Depression, they did prepare the retreading industry to jump in and keep the country rolling during World War II. Due to shortages of imported raw materials like natural rubber and petroleum, retreading—which used only half of the petroleum of a new tire—really burgeoned.
Synthetic rubber was invented to replace natural rubber and was used domestically in retread tread stock. Between 1942 and 1944 the retreading industry expanded 500 percent. Retreads met virtually all civilian passenger tire needs, since sales of new tires and tubes were strictly rationed.
The armed forces relied greatly on retreading and repairing, sponsored research and published numerous guidelines for proper repair and retread procedures. Unfortunately, the first synthetic rubber used during war time had poor adhesion qualities that resulted in a large percentage of tread separations. Memories of these retread failures still haunt the industry.
After the war, improvements were made in synthetic rubber and natural rubber was once again available. As a result, retreading continued to grow and flourish and morphed from a custom-made service, in which tires were retreaded and repaired as needed, to a mass production industry in which retreads competed with new tires for a share of the replacement tire market.
Electrically heated molds made their appearance, enabling small retreaders to invest in individual molds and expand production gradually. Major improvements were made to buffing rasps when B&J Manufacturing invented a new buffing rasp made of individual blades that produced a more even-textured buffed surface than the old tack rasps that were literally perforated hubs into which case-hardened tacks were placed. By the end of the 1940s there were nearly 9,500 retread shops.
The 1950s brought about Bobbie-soxers, pompadours and tubeless tires. All of these were a problem to my mom, who had to deal with my older, teenage sisters and brother and tires that were prone to casing separation that resulted from air permeation. Retreaders were naturally more affected by the new tubeless technology that hadn't yet perfected the impermeable inner liner. Tire venting and inner liner spraying were among the many techniques retreaders used to detect and prevent casing separation.
Bandag Inc. also made its debut at this time. In 1957 Roy Carver introduced a German technology to the U.S. that vulcanized a fully cured tread to a buffed casing with a thin layer of uncured rubber in a chamber that cured the tire at only 194 degrees Fahrenheit instead of 285 F typically used in other retread systems.
A metal band was placed around the tread to hold it in place and aid in curing. This new technology was far from perfected when in-troduced to U.S. retreaders who experienced a high percentage of tread separations. Only after several years of persistence and determination was the process perfected to use an envelope instead of the metal band for curing. Then it was accepted by retreaders.
In addition to Bandag, many, many other companies entered or became leaders in the retreading industry. By the end of the decade there were an estimated 12,300 retreaders in the U.S. who focused primarily on passenger tire retreading. Truck tire retreading was a steady, but lesser market.
Firestone Tire & Rubber Co., Goodyear, B.F. Goodrich and General Tire Co. all operated numerous company-owned retread plants across the country. The growth and profitability was in retreading 14- and 15-inch tires in highway and aggressive mud and snow tire designs. This was the heyday of passenger tire retreading.
The 1960s and '70s were turbulent periods—not only for our nation and my family, but for retreading as well.
While the retread plant population began the decade at well over 12,000, the number of plants began to dwindle. This decline was due to several factors:
c A trend toward larger facilities, resulting in retreader consolidation;
c Fiberglass-belted tires that presented high reject rates and many problems to the retreader;
c Radialization, which required the purchase of new and expensive radial design and dimension molds;
c Changing tire sizes;
c Government control and involvement; and
c An increase in liability litigation.
Due to the increased problems and costs associated with retreading, many passenger tire retreaders simply called it quits.
Truck tire retreading during the 1960s and 1970s remained virtually stagnant with the use of bias tires. However, in the late 1970s radial tires were introduced to the U.S. trucking industry, which changed the face of American retreading for years to come.
Radial truck tires were relatively expensive compared to bias truck tires. But tire manufacturers promised that they could be retreaded several times, which in the long run made them more economical than bias tires. As a result the trucking industry began the conversion to radials.
Retreaders found that a smaller investment could be made in precure retread processes to retread the unforgiving radial tire dimensions, as opposed to purchasing relatively expensive and dimensionally restrictive full circle or segmented molds. As a result, the retreading industry—which had been predominantly mold cure since as far back as my mother can remember—became dominated with precure retreaders.
Bandag remained the leader, but almost all of the other tread rubber manufacturers entered precure tread manufacturing as well. Mold manufacturers declined.
By 1979 tire retread plant population in the U.S. had dropped to 3,400.
Tire retreading in the 1980s really began to embrace globalization. European companies began marketing equipment and techniques in the U.S. Italian companies like Marangoni S.p.A., Cima Impianti S.p.A., Europress and CISAP S.p.A. introduced presses, buffers, molds and extruders. Collman GmbH from Germany and SIO A.p.S. from Denmark brought over buffers and the English company Barwell International Ltd. introduced a new type of extruder. All of these efforts were focused primarily on truck tire retreading.
Non-destructive inspection (NDI) machines first appeared in the 1980s. Bandag introduced its NDI machine and before long other retread companies came out with their “high-tech” inspection equipment that used ultra-sound, holography and high pressure. This equipment was really needed since the new radial truck tires were plagued with separation problems that would otherwise go undetected.
Passenger tire retreading, for the most part, met its death in this decade. In 1980 some 25 million passenger tire retreads were sold. By 1990 this number had dropped to 13 million. While mud and snow tires had always been a mainstay of passenger tire retreaders, their numbers declined due to the appearance of all season tires as original equipment on vehicles and in the aftermarket.
The final deathblow came from the other side of the world as low-cost European and Chinese tires entered the U.S. market. To compete, retreaders reduced the quality of their products to make them cheaper. Their performance worsened, and some retreaders believe passenger retreads eventually died in disgrace.
By 1989, the number of retread plants in the U.S. dropped to 2,100.
The 1990s and the New Millennium ushered in the era of “high-tech,” computer-controlled retread equipment. Goodyear introduced its UniCircle process and Marangoni brought its Ringtread technology from Italy in which the precured treads are made in spliceless circles that are stretched around the casings by special building machines. Bridgestone/Firestone opened its Oncor mold cure plant in St. Louis for the mass production of retreaded truck tires.
Non-destructive casing inspection technology is really credited with improving retread quality during this period. Ultrasound was greatly im-proved and X-ray became available to retreaders. Shearography was the new and improved offspring of holography, and it gave birth to differometry, which is specifically designed for high-speed production and testing.
Computer controlled buffing technology made its debut at this time. This technology results in more precise roundness and consistency of the prepared casing and has greatly improved retread performance. Also introduced were computer-controlled builders and extruders that apply treads without stretching the splice and build to precise dimensions. This equipment also reduces labor and improves quality.
In addition, state-of-the-art compounding produces treads that last longer, run cooler and have a higher resistance to irregular wear.
Today there are fewer than 850 retread plants producing well over 17 million retreaded truck tires—which is more than half the replacement truck tire demand. Although the number of plants has declined, the number of retreads produced annually at these facilities has increased dramatically to more than 19 million in 2003 from 16 million in 1982.
While my mom has seen a great deal of change in the past 94 years, I'm sure there's a great deal more to come as the retread industry continues to evolve with the times. What's ahead? Who knows? Like Forest Gump's mother said: “Life is like a box of chocolates. You never know what you're going to get.”
For those of you getting older and worrying about it, take a lesson from my mom. She brags to everybody about how old she is. I think she wants people to know why she looks as she does. After all, she's traveled a long way and a lot of the roads weren't paved.