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 introduced 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.