To most car owners, they’re round and black and wear out too soon. They’re an expensive pain in the ass, replaced only when the tread wears thin enough to risk a ticket from a pedantic cop.
To a Bugatti Chiron owner, though, tires are the only reason theirs is the fastest street-legal production car in the world. Those 1,479 ponies? The trick aerodynamics? The carefully tuned suspension and steering and brakes? All worthless without tires capable of keeping the Chiron in touch with terra firma at 261 mph and beyond.
The specially developed Michelins hugging the Chiron’s massive forged alloy wheels are arguably the car’s singular technical achievement. They make the big Bugatti’s raison d’être a reality.
Just 15 years ago tire manufacturers scoffed when Bugatti engineers asked whether they could build a tire for the original Veyron. Impossible, they said. The Veyron was too fast, too heavy. No tire could cope with the physics, let alone be durable enough to be used on regular roads in all weather conditions. Only Michelin was brave enough to try. And even then its tire came with plenty of caveats.
Each Veyron tire took an hour to build by hand, a set of four cost $42,000, and they lasted maybe 6,000 miles. At 253 mph, they’d last a maximum of 15 minutes before the heat and enormous centrifugal forces would simply tear them apart. Fortunately, the Veyron would run out of gas in less than 10 minutes at that velocity. To guarantee the integrity of the bead seal, Michelin would only allow two sets of tires to be fitted to a Veyron rim before the rim had to be scrapped. A set of replacement rims cost a cool $69,000, which made fitting that third set of tires a $111,000 proposition.
Michelin learned a lot from the Veyron experience. During the Chiron development program, Bugatti engineers made 18 trips to Michelin’s R & D center in Clermont-Ferrand, France. Michelin used an aircraft-tire testing rig during the process because this was the only piece of equipment that could spin a prototype tire fast enough to replicate the huge loads expected at V-max.
The Chiron tires—285/30R20 for the front and 355/25R21 for the rear—deliver increases in contact patches of 14 percent and 12 percent, respectively, compared with those on the Veyron. They can handle almost 3,700 lb-ft of torque where the rubber meets the road, and most important, they can endure 3,800 times the force of gravity at 261 mph without exploding, all while delivering good ride quality and good grip regardless of the weather.
The new tires are also easier to fit than those used on the Veyron. Michelin has dispensed with the complex PAX run-flat system, which also required special and expensive asymmetric rims. Bugatti won’t give details yet, but it says the new tires allow lower operating expenses. Apparently even gazillionaires hate paying for tires.
After his record-breaking 268-mph run in the 1,200-hp Veyron Super Sport at Ehra-Lessien in July 2010, Bugatti test driver and former F1 racer Pierre-Henri Raphanel said the only thing preventing the Veyron from going beyond 270 mph was its tire technology. Bugatti CEO Wolfgang Dürheimer promises the more powerful Chiron will easily blow by the mark set by the Super Sport and become the fastest production car in history.
Does that mean 270 mph? 275? 280? We’ll see this summer. Whatever the final number, Bugatti now has the tires to make it happen.
