When the first C6 ZO6 prototype was shown at the Detroit auto show in 2005, it was displayed beside the newly revised factory race Corvette, the C6.R. While GM officials took pains to highlight the mechanical similarities between the two cars, there was one key area in which the flagship street and competition Vettes continued to diverge: the brand of their tires. The racer was fitted with racing slicks from Michelin, while the production car wore Goodyear F1 EMT run-flats. But unbeknownst to most showgoers, Corvette Chief Engineer Tadge Juechter and company were developing the upcoming 2009 Chevrolet Corvette ZR1 supercar on all-new Michelin rubber.
The switch mirrored an earlier move on the part of Corvette Racing. While the C5-Rs used Goodyears from 1999 through the end of 2003, these tires were dropped after a crushing loss to the Michelin-shod Ferraris at the Corvette's 50th anniversary race at the '03 Le Mans. The team studied the race data and determined that the Michelins provided Ferrari with the winning edge. The 2004 season proved a huge success for the now-Michelin-equipped Vettes, including a class win at Le Mans. So perhaps it was only natural that the Corvette engineering team would look to the French tire maker when developing the ZR1.
When the ZR1 was unveiled in 2007, the big news-besides the massive brakes and 638hp horsepower engine-centered around the car's Zero Pressure (run-flat) Michelins. The new tire received rave reviews from the automotive press, prompting many Corvette owners to seek them out as replacement rubber for their own cars. But while Michelin had released an all-season Zero Pressure tire for the C5 in 2001, the company lacked a comparable offering for the C6.
That changed in 2008, when the Pilot Sport 2 Zero Pressure (PS2ZP) was introduced for both the fifth- and standard sixth-generation Vettes. But much to the surprise of Z06 owners, the PS2ZP still wasn't available in OE sizes for their car. The reason? During extensive testing, it was found that the existing PS2ZP wasn't much better than the Z06's factory rubber. As a result, Michelin decided to suspend the release of the tire until sufficient performance improvements could be effected.
The tire was revamped, and in August Team VETTE was invited to the Spring Mountain Motorsports Ranch to compare the new Z06-sized (275/35 ZR18 and 325/30 ZR19) PS2ZP tire with its OE counterpart. Spring Mountain is located in Pahrump, Nevada, in the southwest corner of Nye County. It's essentially the middle of nowhere-45 miles west of Las Vegas and 60 miles east of Death Valley-which makes it a perfect spot for a racetrack. In addition to its full, 3.1-mile length, the Spring Mountain course can be divided into 1.5-mile upper and 1-mile lower sections.
Our day started out with introductions and an overview of the facility, including a slow drive around the course. Corvette Racing driver Ron Fellows delivered opening remarks and talked a bit about Spring Mountain's ZR1 driving academy, which is included with the purchase of the car. We then received a technical overview of the new Z06 PS2ZP tire, given by Michelin brand category manager Nicolas Goubert.
According to Goubert, Michelin's goal was to give the Z06 PS2ZP the best possible combination of wet and dry performance. This was accomplished by combining two distinct tread patterns into one tire. The tire also includes Michelin's high-performance Variable Contact Patch technology, or VCP. When traveling in a straight line, the shape of the contact patch is symmetrical. But when cornering, the weight of the car increases the outside contact patch of the tire. This unique feature ensures excellent control in all conditions.
It was during this technical review that we learned that Fellows was actively involved in the development process. Thanks to efforts of the Michelin engineers, the ALMS veteran is able to lap the Spring Mountain course a full 4 seconds faster on PS2ZPs than on the OE Z06 tires.
When our technical briefing was completed, we moved to the short course to drive Z51 six-speed Corvette coupes. We lapped on both conventional (non-run-flat) and Zero Pressure Michelins and felt very little difference between the two. After this demonstration we headed to the skidpad, which was filled with water on one side and dry on the other. The new Michelins cut through the water like a razor and provided amazing wet traction. The tires' transition from wet to dry was similarly remarkable, and even under hard braking and corner turn-in they displayed impressive grip. As a bonus, they also proved very quiet. The OE tires, by contrast, skipped over the water at the same speeds and required significant steering correction to navigate the wet course. They also had less grip on the dry portion and were quite noisy when pushed hard.
The final exercise of the day involved driving a Z06 equipped with PS2ZPs followed by another one wearing the OE tires. Once again, the Michelins provided plenty confidence at the limit and were remarkably quiet as well. Braking performance was also impressive. The OE tires weren't as compliant and protested loudly when pushed.
Our conclusion? If your Z06 is in need of new tires, Michelin's PS2ZPs are worth a very close look. While these new tires may carry a 10-15 percent price premium, they appear to be worth every penny. We'll find out in future issues, as we mount a set on a C5, subject them to a 1,000-mile road trip, and even wring them out on a track test. Stay tuned.