Think of "hot" or "cool" cars. The superlatives usually mean the same thing in the automotive vernacular and generate super-macho names like Porsche Carrera GT, Dodge Viper, Ferrari Italia and Bugatti Veyron.
The monikers invoke images of bright colors streaking through mountain passes on the Autobahn and conjure dreams of one parked in a lucky American’s driveway.
Thankfully, supercars are equipped with super tires, their sleek profiles and aggressive tread patterns complementing the vehicles’ appearances. This begs a rhetorical question: Has the tire industry created a subtle link between “Y” speed ratings awarded super tires, masculine images bestowed on supercars, and the Y-chromosome containing the male gene?
Boasting from 600 to more than 1,000 bhp of muscle, each exotic, steroid-injected street-legal coupe and luxury model has more than enough juice to achieve subsonic speeds that could lift them into the air. The Veyron’s manufacturer claims the car needs only 275 bhp to reach 155 mph, leaving 726 bhp in reserve. Just in case, we suppose.
Of course, aerodynamics designed into car models keep them firmly planted on the road. Sculpted in wind tunnels, a vehicle’s front splitters, back spoilers, low ground clearance and many other features generate enough downforce to offset upward propulsion forces.
The downforce – well on its way to 1,000 pounds – meets the pavement through four contact patches. When accelerating to 60 mph in under four seconds, stopping from the same speed in less time, delivering superior handling and aggressive cornering on dry pavements are added to performance demands, it’s a lot to expect from the tires.
Drivers may not tap into 200-plus mph capabilities on U.S. highways, but they can benefit from the other inherent performance characteristics.
Michelin, a major supplier to ultra-high performance auto manufacturers, is currently launching a new super tire into replacement markets worldwide. The Michelin Pilot Super Sport, touted as the fastest series-produced tire on racetracks, is due at U.S. tire dealers in April of this year.
The Pilot Super Sport tire is intended for day-to-day use on super sport and street-legal cars tuned and modified for ultra-high performance, according to Kip Newton, Michelin’s product category manager for UHP tires. “Safety and driving enjoyment are perfectly balanced for everyday road use as well as the race track,” he says.
Both traits are important to drivers. Michelin cites a 2009 study conducted in the U.S., five European countries, Russia and China that states 62% of the 9,000 respondents mentioned the important role that tires play in their car’s safety and handling performance.
Michelin’s development team of engineers work directly with auto manufacturers to create supercar tires for OE vehicles and the replacement tire market. In a series of responses, Newton provided insights into the technology behind his company’s high-performance tire program.
Tire Review: What is a super tire’s speed rating?
Newton: Supercars typically use Y speed-rated tires designed for sustained speeds of 186 mph. Parentheses enclosing the Y indicate a tire exceeding 186 mph and is typically set by the manufacturer in 12.5 mph increments. An Italia may have a (Y) speed-rated tire for 211 mph.
TR: Why are 200-mph-rated tires marketed in the U.S?
Newton: In normal U.S. 55-75 mph speeds, higher speed-rated tires provide an extra degree of security. However, the tires are typically approved for use worldwide, so they’ll likely find their way on high-speed roadways.
TR: What are the handling criteria that define a supercar tire?
Newton: Handling is a complex interaction between vehicle and driver. Michelin uses several handling criteria, including sublimit steering for feel, effort, gain and linearity, as well as near-limit and limit criteria such as lateral firmness, progressivity and lane-change stability.
TR: Are supercar tires interchangeable from one car to another?
Newton: Most supercar OE tires are designed for a specific application.
TR: Talk about the anatomy of Michelin’s new Pilot Super Sport tire.
Newton: The chassis of the tire contains steel belts, radial plies and a cap of Ceinture Twaron, a high-density fiber for high-speed stability also used in aeronautics and protective military gear. A bi-compound tread uses different rubber compounds on each side: on the outside is a unique carbon-black-reinforced elastomer for endurance when corners are tight; on the inside is a high-grip elastomer that breaks through the water’s surface and adheres to the road.
TR: How is the tire footprint controlled at high speeds?
Newton: Variable Contact Patch technology manages the footprint shape during cornering. The pressure of the rubber contact on the road surface, and consequently tire temperatures, are spread evenly across the tire’s contact patch. Although the patch’s shape changes when cornering, the amount of rubber in contact with the road remains the same. Variable tension within the Ceinture Twaron material contains or holds the high centrifugal force at the center of the tire to a different level than its sides.
TR: What are the biggest threats to tires at high speeds or during aggressive maneuvering?
Newton: Centrifugal, cornering, acceleration and braking forces act on tires, producing tire deformation and creating changes in temperature and the pressure across a tire’s contact point on the roadway. The stiffness of the tread compound and pattern is critical to managing a tire’s high speed performance.
TR: What “communications” go on between a supercar’s tires and the driver?
Newton: The interaction between a driver and his or her vehicle is critical to a supercar’s performance and the tires are vital to this interface. After all, the tires are the only connection to the road surface. Michelin test drivers work closely with OE test drivers to ensure that our tires impart desired communication. In particular, steering precision that includes feel and torque allow a driver to accurately steer the car on the road at high speeds.
TR: Is something built into a tire and wheel system to protect a vehicle and driver in case of a sudden blowout?
Newton: Run-flat technology is currently used in supercar tires, including Michelin’s Pilot Sport PS2 ZP fitted for the Corvette ZR1. It provides high-speed stability in case of a blowout and eliminates the need for a spare tire, which reduces the vehicle’s overall weight and provides more car design options.
TR: What role has auto racing played in supercar tire development?
Newton: Racing and passenger tire development are linked on two levels. First, ongoing technology transfers occur. Twaron high-density fiber use and Variable Contact Patch technology are directly derived from racing. Second – and critical to our company’s success – our people and intellectual property are moved in and out of racing and passenger tire development assignments. For example, a tire designer who has worked with General Motors on its Corvette ZR1 and Michelin PS2 fitment is the same person who supports Corvette’s American LeMans Series racing activities.
Michelin affirmed that the information and technology derived from motorsport racing were crucial in satisfying the requirements of different high-profile carmakers. While each supercar manufacturer has its own philosophy and ultra-performance criteria, all of them agree on at least one point: a tire that is certified must highlight and enhance a vehicle’s personality and be suited for both everyday road use and track driving without compromising safety.