Michelin Pilot Sport PS2 ZP Tire Test
Burning Rubber In The Desert Heat
Having participated in Spring Mountain Motorsport Ranch’s 1-Day Corvette Driving School – recently renamed the ‘Ron Fellows Performance Driving School’ in recognition of this legendary Corvette Racing driver’s direct involvement with the program – I was well aware that this 5-star facility owns an impressive fleet of C6 Corvettes including many 405-hp Z51s and 505-hp Z06s as well as several new 638-hp ZR1s. The Ron Fellows link runs deeper than just the school though – he also played a key role as a test driver during the development of Michelin’s highly anticipated Z06-specific Pilot Sport PS2 ZP tire as well as the factory-installed ZR1 PS2s.
|1. Michelin Pilot Sport PS2 tires are the factory tire on many of today’s highest performance brands including Porsche, Mercedes-Benz and Bugatti.
2. Michelin PS2’s are also the OEM choice on the fastest and most powerful Corvette ever built by Chevrolet, the 638-hp C6 ZR1.
3. Z06 Pilot Sport PS2 ZP (zero pressure) tires feature run flat technology and a unique asymmetric tread pattern and a customized tread compound.
A LITTLE HISTORY
In case you’re wondering why Michelin – a company that has been traditionally more focused on high performance European brands like Porsche and BMW – has developed such a strong interest in the Corvette, it all started when Corvette Racing switched to Michelin racing slicks back in 2004. As Ron Fellows explained during one of the classroom debriefing sessions during the PS2 ZP test day at Spring Mountain, for Corvette Racing the 24 Hours of Le Mans in 2003 was the turning point, when a Prodrive Ferrari 550 defeated them. Requiring half as many tire changes, it was clear that the Ferrari team’s choice of the longer lasting Michelins was the difference in the race, so the Corvette Racing team made the switch to Michelin and reeled off three consecutive Le Mans victories from 2004 to 2006, as well as 48 American Le Mans Series GT1 wins in 54 race starts.
Given their success on the race track, it was only natural for Corvette and Michelin to expand their relationship into the passenger car market. With 82 different sizes and technical homologation on over 80 vehicles including Audi, BMW, Mercedes, Lexus, Porsche, Dodge Viper and the new Corvette ZR1, Michelin has a lot of experience tuning the Pilot Sport PS2 for different applications. And that experience extends well beyond OEM applications to include highly modified Corvettes like those produced by Callaway, Hennessey, Pratt and Miller, and Specter Werkes.
In the case of the C6 Z06 PS2, that tuning includes the integration of Michelin’s Zero Pressure (ZP) or run-flat technology that uses a rigid inner shoulder to provide carrying capacity in run-flat conditions and as an added benefit also helps the tire generate an amazing 1g of lateral acceleration in the corners. With a unique asymmetric tread pattern with large outer shoulder blocks for optimized dry grip and a higher groove-to-rubber ratio on the inner tread area for enhanced wet traction, Michelin also adjusted the two compounds used in the PS2 ZP to provide maximum dry and wet grip while retaining wear characteristics on par with their standard PS2 offerings. The flexible outer shoulder of the PS2 ZP also servers to enhance what Michelin calls Variable Contact Patch (VCP) technology that allows the contact patch of the tire to adapt more quickly to changing loads and conditions (eg. cornering vs straight line acceleration). The softer outer shoulder also helps reduce ride harshness and road noise, characteristics that run-flat tires are often criticized for.
Spring Mountain Motorsports Ranch: A Go-Fast Oasis
Just 60-miles from Las Vegas, Spring Mountain Motorsports Ranch is 193-acres of 5-Star motorsports paradise in the Nevada desert where visitors and members alike enjoy the following amenities:
• Two road courses that can be joined to form the 3.5-mile 20-turn big track
Around Spring Mountain’s 1.5-mile 10-turn ‘Radical Loop’ circuit, the performance gap between the brand new OEM Goodyear Eagle F1s and the Michelin PS2 ZPs equipped on the school’s fleet C6 Z06s was dramatic. Attack corner entry and the OEM front tires were quickly overwhelmed, causing the front end to wash out in a frustrating display of understeer. By comparison, the PS2 ZPs provided impressive front end grip that allowed higher corner entry speed and earlier application of the go-pedal.
Behind the wheel of the OEM tire-equipped Z06s a lot of steering and throttle adjustments are required to manage turn-in understeer and mid-corner and corner-exit oversteer, all the result of comparatively lower grip levels. But behind the wheel of the PS2 ZP-equipped Z06’s the driving experience is transformed by grip that allows far more of the Z06’s braking, cornering, and accelerating power to be put to use.
Initially it’s the lack of understeer and higher cornering speeds provided by the PS2 ZPs that stands out, but while chasing an OEM tire-equipped Z06 the superior straight line (braking and accelerating) performance of the Michelin’s became increasingly apparent as well. Although we were not taking lap times, around this relatively short and technical circuit, the time saved by equipping the Z06 with Michelin PS2 ZPs would surely be measured in seconds rather than tenths of a second. That may not sound like much to the uninitiated, but to motorsports enthusiasts and weekend warriors who take their Corvette to the track, that is a huge difference.
On the half-wet half-dry autocross course, the PS2 ZPs highly refined performance characteristics and general superiority over the OEM rubber was just as obvious. On the wet portion of the course, the OEM tires suffered terminal understeer if corner entry speed was a little too high, and hydroplaning under braking was also easily induced by too aggressive an application of the brake pedal. Too much gas also resulted in tire spin rather than forward motion.
The Michelins, on the other hand, generated far more cornering grip in the wet and a very balanced feeling that allowed for some easily controllable tail-out shenanigans. The wet condition oversteer does come on pretty quickly with the PS2 ZPs though, a characteristic that may catch some drivers out the first time they experience it. Where the Michelins felt the most dramatically superior to the OEM tire was in the wet/dry transition zone. Here the Goodyears felt nervous and unpredictable, whereas the PS2 ZPs continued to feel balanced and responsive even when pushed well beyond the limit of adhesion.
The single most effective upgrade you can make to just about any car is its tires. In the case of the C6 Corvette Z06 this is especially true, given the phenomenally high performance potential of this high horsepower beast and the dramatic performance gains experienced at Spring Mountain Motorsports Ranch while testing Michelin’s Pilot Sport PS2 ZP tires. Although these Z06-tuned PS2’s are considerably more expensive than the OEM rubber ($1,820 for a complete set as compared to the OEM Goodyear’s at $1,430), if you’re the type of driver who finds yourself at the track on weekends or wanting more grip on the street then it’s money very well spent. The additional wet and dry grip will not only provide additional performance and safety on the street, your Corvette buddies will be eating your dust at the track if they haven’t made the same investment.
Wanna Go Even Faster? Michelin’s Got You Covered
If you’re a serious track rat, then you may be looking for even higher dry grip levels than Michelin’s PS2 tires can offer. Michelin’s Pilot Sport Cup tires, a DOT-approved (meaning street legal) option that comes standard on track-specials like the Porsche 911 GT3 and Dodge Viper ACR, provides exactly that. As we experienced at Spring Mountain on their C6 Corvette Z06’s and ZR1’s, the Cup tire opens up a whole new level of performance in the dry, allowing for banzai-style late braking and eye-popping cornering speeds. Be aware that these tires do not offer wet or cold weather traction on the level of a normal summer tire, but for warm and dry conditions nothing will unlock the performance potential of your high performance vehicle more than a set of “r-compound” tires like Michelin’s Pilot Sport Cup.