Tires are never the sexiest part of the car. Enthusiasts look at attractive bodywork, high-performance engines or luxurious interiors when fawning over their favorite autos. Tires are almost always an afterthought.

There could be a couple of explanations for this. Tires are consumable and interchangeable—they are swapped on the whims of owners and weather, and the tread will inevitably wear beyond traction. Exciting innovation in tire design is rare. Despite some materials improvements, radial tires have been the standard for 60 years.

But at this year's Geneva Motor Show in early March, tire manufacturer Goodyear unveiled two concept tires that rivaled some cars in press attention. One concept that Goodyear rolled out could help the adoption of all-electric vehicles. The other could improve vehicle safety and even could become standard on autonomous cars. Both have the potential to change the way consumers think about tires. Goodyear says it envisions a future where tires are expected to be multi-functional, just like many other components in our evolving automobiles.

EVs Get a Boost

Goodyear's BH-03 will help electric vehicles (EVs) extend their driving range by generating electricity through materials innovation. The tire is made from a thermo-piezoelectric material that captures overlooked sources of electrical energy. Engineers faced the challenge of incorporating this material in a component that takes so much abuse, without sacrificing durability or elongation.

Goodyear's BH-03 concept tire could recharge a dead car battery. Source: GoodyearGoodyear's BH-03 concept tire could recharge a dead car battery. Source: Goodyear First, the tire color is described as “ultra-black," which Goodyear says maximizes the amount of thermal energy it absorbs. If the car were to sit idle long enough, it could conceivably recharge an empty battery. Heat also is captured from the tire's cyclic deflection as it rolls. This creates internal friction in the elastomer that generates heat, which the tire's thermoelectric elements also harvest. So much heat is collected that a heat-sink mechanism is needed to prevent it from degrading the quality of the rubber.

A piezoelectric liner, likely a ceramic-polymer composite, is integrated into the tire. As the tire rotates, its section height (that is, measurement of the sidewall) shrinks when under load, but rebounds as the load is removed. The piezoelectric liner converts this dynamic oscillation into another source of energy. Not only does the BH-03 gather energy from unlikely sources, it also recaptures some of the energy spent to power the vehicle. Goodyear has not released figures around how much energy four BH-03 tires could supplement to a typical EV.

The Transforming Tire

A growing trend among auto manufacturers is to include driver or computer-selected operating modes. Such modes optimize engine performance and fuel efficiency according to the vehicle's operational needs. For example, highway mode provides fuel efficiency at high speeds, city mode delivers a more responsive engine, weather mode ensures better traction during rain or snow, and off-road mode helps navigate diverse terrain. However, these operating modes typically only affect how the powertrain operates, not the traction between the tire and pavement.

The Triple Tube could help identify adverse road conditions. Source: GoodyearThe Triple Tube could help identify adverse road conditions. Source: Goodyear Yet with Goodyear's "Triple Tube," a tire that adapts to road conditions, drivers may be better assured the optimal contact patch (geometry of contact between tire and road) for several driving conditions. It resembles Goodyear's previous work in air maintenance technology.

The Triple Tube consists of four internal membranes—the main chamber, as well as three adjacent tubes that are internally positioned along the tire's section width. An internal pump controls pressure, moving air between tubes and the main chamber. For typical driving, each tube maintains an identical pressure for optimal safety and fuel economy. For performance driving, the pump reduces pressure in the shoulder tube to improve handling. In wet conditions, the central tube is inflated more than the other tubes to reduce hydroplaning.

One challenge for autonomous vehicle development has been identifying adverse road conditions and altering vehicle behavior to ensure safety. Tires that adapt to driving conditions would assume some of that responsibility.

Many obstacles remain before the BH-03 or Triple Tube sit on retailers' shelves. Since they remain as concepts, Goodyear would not provide exact specifications for either product. Manufacturing a car that leverages these technologies appropriately will also take cooperation between automakers and tire-makers. Also, how will other tire manufacturers enter the advanced tire market?

What is clear is that tires need to progress as vehicles do, even if the BH-03 and Triple Tube remain nothing more than auto-show concepts.

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