Tires of Today Vs. Tires of the Past

Tire technology hasn't just evolved in parallel with automobiles as a whole; in many ways, it has driven the development of automobiles. At one time, the typical automotive tire was just hollow rubber cord wrapped around what was essentially a buggy wheel. In fact, it would be fair to say that tire tech is what ultimately limits automotive development, regardless of whether you're talking race cars or just the average putt-about.

Construction

Tires have advanced in two major ways since automobiles first hit the streets -- or tracks, as the case may be -- over a century ago. The invention of vulcanized rubber preceded the first major revolution in tire development; but, if you're going to draw a line in the sand to delineate eras of development, then it has to be in 1975 when Michelin introduced the very first radial passenger car tire. Previous bias-ply tires used a cord construction that ran diagonal to the tread direction, which yielded a fairly smooth ride, but terrible performance. Radial tires use reinforcing bands that wrap around the tire's circumference, which makes for a far stronger tire, lower rolling resistance and superior performance on pavement. The trade-off is that radials aren't as puncture resistant, and don't provide for the off-road performance that bias-plies do.

Going Tubeless

Once upon a time, all tires used inner tubes. BF Goodrich first patented the tubeless tire in 1952, and a scant three years later they were factory-standard on nearly every new automobile produced in the US. Tube tires maintain several disadvantages over tubeless tires, the primary one being that inner tubes will tend to rub on the inside of a tire's outer liner at speed. This rubbing creates a great deal of heat, which reduces speed potential, tube life and safety at sustained freeway speeds. Tubeless tires were a tremendously important step not only tire evolution, but in the evolution of our nation. A brief peek at history will reveal that Dwight D. Eisenhower signed the Federal Highway Act for the construction of a United States interstate system in 1956. Ike justified the interstate system as a cold-war defense measure, but the high probability of tire failure and visions of daily pile-ups are what kept Congress from passing the act a decade before tubeless tires hit the scene.

Sizes

Laugh if you'd like to at the buggy-car tires of the 1910s and 1920s, but there was a certain logic behind it at the time. Most turn-of-the-century roads were little more than dirt tracks, churned to mud on a daily basis by horses and horse-drawn carts. Those carts left a unique set of ruts in the road, places where the dirt was compacted enough so as not to bog down the first automobiles. In fact, as cars followed the roads and road construction followed cars, we actually wound up keeping most of the old buggy's proportions in terms of wheelbase and track width. Tires have gradually gotten far wider with respect to the car's overall track width, and sidewalls have gotten shorter to enhance on-road handling. We have radial tire construction to thank for the tire's new-found versatility in terms of side. Radial construction allows a tire to keep its shape while remaining flexible enough for daily use, which allowed us to make sidewalls shorter. The radial's high traction-to-resistance ratio allowed us to make tires wider, without making them unduly heavy or a burden where fuel economy is concerned.

Tread Design

Tire tread has evolved in a markedly subtle way, one that takes a trained eye to appreciate. Decades of computer development and hydro-dynamic engineering have allowed us to engineer tread patterns that perform better in the rain than most tires of 20 years ago could in the dry. Carefully shaped tread blocks, tread voids, rain grooves and water sipes not only channel water away from rubber contacting the road; they maximize point-contact pressure to extract maximum traction from the rubber that does touch the road. Specialized winter tires take this to an extreme, increasing point pressure so much that ice crystals squish back to a liquid state. It is as true today as it ever was that material science drives tread pattern technology. Experiments in rubber compound technology during the 1980s and 90s aimed at exploring the radial tire's limits resulted in compounds capable of maintaining fine tolerances and complex shapes under extreme duress, which is what makes today's advanced tread design possible.

References

• "A History of the World's Racing Cars"; Hguh and Frostick; 1965
• "The Golden Age of Formula One"; Rainer W. Schlegemich
• "Race Car Engineering and Mechanics"; Paul Van Valkenburgh"; 2001
• "The Off-Road and 4WD Book"; Jack Jackson; 1999
• Industrial Utility Vehicle Magazine: Tires Have Evolved
• The History Channed: This Day in History - BF Goodrich Announces Development of Tubeless Tire