Making Firestone Pnuematic Tires
In 1984, a sturdy brick farmhouse built in 1828 was dismantled at its original location and rebuilt at Greenfield Village near Detroit, Mich., by the Ford Foundation. In the late 1950s, however, the house still stood on the Firestone Homestead Farm east of Columbiana, Ohio. During that time, I was sent to the Firestone house to repair the telephone. Hanging on the wall just above the phone was a framed 1930s-era photograph of all the farm’s machinery, including a Farmall Regular tractor and a complete line of horse-drawn and tractor implements, all shod with Firestone tires.
Harvey Firestone, 1868-1938, founded the giant tire company that bears his name and was an enthusiastic proponent of pneumatic tires, not just on farm tractors, but on all farm machinery. He was in the minority: Almost every expert of the time thought the idea ridiculous. In the spring of 1932, balloon tires with a low chevron tread design were fitted to a tractor on the Firestone Homestead Farm. Firestone drove the test tractor in the field to observe the results firsthand.
Steel-lugged wheels provided pretty good traction in soft soil, but were rough riding and shook drivers and machinery to pieces on harder surfaces, such as roads. To preserve road surfaces, many state and local governments passed laws prohibiting tractor use. Farmers had to plank the roads to move their tractors on them, or face stiff fines. Industrial tractors had used solid rubber tires since the early 1920s, but they provided no traction in grassy or muddy fields.
In 1932, Allis-Chalmers engineers equipped a Model U tractor (owned by Wisconsin farmer Albert Schroeder) with a pair of Firestone 48-by-12-inch airplane tires for a test that proved highly successful. After the Schroeder tests, and the extensive testing conducted on the Homestead Farm, much of it done by Mr. Firestone, the first practical, pneumatic tractor tires were offered for sale in October 1932. Allis-Chalmers announced on Oct. 13 that it was offering Firestone air tires as standard equipment for its Model U tractor, making AC the first tractor builder to do so.
Many plowing and pulling matches were staged to prove the superiority of rubber over steel. Virtually all demonstrated that rubber air tires were better. Still, this was the depth of the Depression and farmers were a conservative lot, so acceptance was slow.
During the summer of 1933, Allis-Chalmers and Firestone sponsored tractor races at state fairs throughout the Midwest. Famous automobile race driver Barney Oldfield drove a stock (except for high-speed gears) Allis-Chalmers Model U at speeds of more than 40 mph, even setting a world tractor speed record of 64.28 mph in September 1933.
A publicity photo of Oldfield on tractor no. 999 shows Barney in white shirt and tie, leaning forward with one hand on the wheel and the other on the gearshift, ready to race. The Model U may have had a stock engine, but the wheels, with their white-lettered Firestone tires, are chrome and equipped with big chrome hubcaps. The belt pulley face, exhaust and intake manifolds, carburetor and air intake all appear to be chrome, and the whole tractor glistens like a jewel. All the tractors used on the fair circuit were provided by Allis-Chalmers and, except for Oldfield’s, were manned by AC employees. Of course, Barney always won.
Oldfield’s record was broken at Bonneville in 1935 by racer Ab Jenkins, who drove another AC Model U (on Firestone tires of course) through a measured mile at 67.8 mph. Jenkins, who said the experience was like “riding a frightened bison,” was awarded a fancy belt buckle inscribed with “The World’s Fastest Farmer.” Jenkins’ son, Marv, later said, “Because it was so rough, Dad couldn’t sit down on the seat. He had to stand, and even then it was all he could do to stay on the tractor.”
While these publicity stunts helped break down resistance to air tires, probably the most dramatic argument came from dual tests made in Nebraska in 1934, using the same Allis-Chalmers WC tractor, first equipped with air tires and then with steel wheels. Using steel wheels, 5.62 hp hours-per-gallon of fuel was recorded, with the economy jumping to an amazing 8.18 on rubber tires. The average horsepower hours-per-gallon of fuel attained by all 46 tractors tested during 1930 was just 5.59.
Approximately one million tractors were on U.S. farms in 1932, all with steel wheels. The pounding, jarring and vibration wore out the machines and their operators, and Firestone saw those one million tractors as opening up an entirely new market for his tires.
Many problems faced early tractor tire designers. Crop clearance demanded a high, large diameter tire, while a wide cross section (but not too wide to fit in the furrow) was needed for good soil contact. That contact had to be firm enough for good traction, but not so firm as to cause tire slip on the rim. Excessive air pressure would pack the soil too hard, while too little pressure would cause rim slip. Flat truck rims were used at first, but because of rim slip they were soon replaced by the drop center rims with a tight bead still used today.
Tread design was a big concern. Firestone tried many different configurations, starting with shallow and then deeper chevrons, followed in 1935 by the famous “Ground Grip” design with deeper pairs of angled bars joined to each other for strength. Rival Goodyear touted a diamond tread pattern, before going to angled bars open in the center, while Gillette stuck to a knobby style tread for many years.
In 1935, only 15 percent of new tractors sold had rubber tires, but the advantage of pneumatic tires over steel wheels in fuel economy and performance, not to mention driver comfort, caused the demand for rubber to rise quickly. By 1937, farmers were ordering 43 percent of their tractors on rubber, a figure that jumped to 85 percent in 1939, and 95 percent in 1940. In addition, field change-over of older tractors proceeded even more rapidly. Harvey Firestone’s dream of putting the farm on rubber was well on its way to being reality.
In the next issue of Farm Collector, I’ll relate some firsthand stories about the tractor tire testing program at the Firestone Homestead Farm right after World War II. FC
Sam Moore grew up on a farm in western Pennsylvania. He now lives in Salem, Ohio, and collects antique tractors, implements and related items. Contact Sam by email at email@example.com
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