Michelin and Porsche A shared passion for Ultra High Performance
Porsche / Michelin Relationship Michelin is Porsche’s principle partner for; Street Tires Competition Tires Formal Agreement, International in Scope One of only two such partners, along with Mobil One Joint International Motorsports Activities American Le Mans Series (ALMS) Porsche Michelin SuperCup (PMSC)
Background, Performance Expectations, Care & Feeding All the good stuff.
Performance Ambitions & Results Top Gun in Dry Performance Enduring-racing-type performance in lap times and in worn aspect after hard use. Very competitive performance in damp conditions (and strong performance in wet conditions when proper additional grooving is applied). Michelin Pilot Sport CUP tire brings you next to zero evolution over a club-race distance. Lap times are consistent lap after lap. Less performance dispersion -- Wear aspect and overall life are what you would expect based on lap time consistency--Pilot Sport CUP tire stays ready for more punishment.
Tread and Sidewall Design Tread design must deliver the message! Closed exterior shoulder for maximum dry handling. Relatively open interior for damp/wet conditions. Note: Pilot Sport CUP is NOT directional despite being equipped with angled lateral grooves. The angled blocks provide additional edges for damp conditions, but are not that efficient for lateral evacuation given the reduced tread depth at the shoulders.
Tread and Sidewall Design Sidewall New lettering unique to Pilot Sport CUP tire Michelin logo Obvious “Outside” markings Sidewall includes necessary markings for worldwide utilisation
Features and Benefits FEATURE: RACING-INSPIRED TREAD COMPOUNDING BENEFIT: Superior Adherence and Handling MECHANISM: The Pilot Sport CUP’s tread compounds are formulated to have a maximum energy absorption (hysteresis) at competition operating temperatures (in the neighborhood of 160-220 F). This is an appreciably higher temperature range than the efficient range for standard UHP street tires and provides improved traction and cornering grip for road racing situations.
The objective is to minimize dry adherence differences between Pilot Sport Cup and a slick race tire, while providing outstanding damp wet handling. This seemingly impossible task is made possible through the “tuned” stiffness of the tread pattern. Features and Benefits FEATURE: RACING-INSPIRED TREAD COMPOUNDING BENEFIT: Superior Adherence and Handling DETAILS: Compounding strategy in most cases is to use a coextrusion of two mixes to maximize overall wet /dry performance. The outside shoulder compound is optimized for dry handling, while the inside shoulder has more potential for wet adherence (although it is very efficient in the dry as well).
The tread compounds are mixed alongside our other high performance race mixes in the same plant in central France, and the tires themselves are made alongside our GT racing tires that do battle every weekend. Features and Benefits FEATURE: RACING-INSPIRED TREAD COMPOUNDING BENEFIT: Superior Adherence and Handling DETAILS: Compound tests at the track evaluated best lap times as well as consistency in lap times and tire wear. It’s the same attention to detail that breeds success in storied endurance races like the 24 Hours of Le Mans, the 12 Hours of Sebring, the Petit Le Mans--races where Michelin-equipped racers have dominated for years.
FEATURE: STABLE CENTRIFUGATION OF THE TIRE BENEFIT: Consistent performance particularly at high speed MECHANISM: Centrifugation performance as measured by the growth of the tread diameter and the change in the transverse curvature of the tire’s crown with speed is improved. The idea is to minimize the evolution of the contact patch with speed, ensuring consistent track performance and excellent tire wear--both at the track and on the street. Features and Benefits
Rigid belt package (steel + polyamide) impedes the change in diameter and assures a consistent growth across the width of the tire. DETAILS: Reduced tread depth and tapered tread profile minimize the centrifuged mass. FEATURE: STABLE CENTRIFUGATION OF THE TIRE BENEFIT: Consistent performance particularly at high speed Features and Benefits
Recall that Pilot Sport production tires have been used to establish FIA high speed vehicle records on closed circuits. Test conditions include 100% of rated tire load for the given tire size, 36psi cold starting pressure. Internal testing of high speed capability shows remarkable gains of 50 km/h (30 mph) versus the already-impressive Pilot Sport tire. FEATURE: STABLE CENTRIFUGATION OF THE TIRE BENEFIT: Consistent performance particularly at high speed DETAILS: Features and Benefits
FEATURE: OPTIMIZED CROWN ARCHITECTURE STIFFNESS BENEFIT: Extreme Cornering Power for Rapid Steering response and Confident Cornering MECHANISM: Overall stiffness of the internal architecture is increased (versus Pilot Sport). The result is quicker steering response and a reduced rear axle slip angle for equivalent lateral acceleration. A driver corners with more confidence when the rear slip angle is diminished, and the yaw response of the vehicle is quickened appreciably. Features and Benefits
DETAILS: Asymmetric tread pattern delivers a boost in cornering power. Tread depth is approximately 5 mm (6/32nds of an inch) in the center of the tread pattern with a taper to 2.5 mm (or 3/32nds) at the shoulder edge of the contact patch. Belt package was inspired by our endurance racing tire developers and finely honed at the track. FEATURE: OPTIMIZED CROWN ARCHITECTURE STIFFNESS BENEFIT: Extreme Cornering Power for Rapid Steering response and Confident Cornering Features and Benefits
FEATURE: STABLE CENTRIFUGATION OF TIRE Photos compare Pilot Sport (black) and Pilot Sport CUP (red) Pilot Sport CUP grows less than the world-class Pilot Sport between 0 and 300 km/h! 225/40 18 v=300 km/h225/40 18 profil gonfle 0 km/h300 km/h
Care & Feeding of Pilot Sport CUP PRESSURES SUSPENSION ALIGNMENT TEMPERATURES HEAT CYCLING SHAVING RECUTTING FOR HEAVY WET CONDITIONS
Care and Feeding PRESSURES General Guidelines: Road Racing : 25-28 psi cold (front/rear) 32-36 psi hot (front/rear) is your typical target Autocross (slalom): Looking for same range (of hot pressures-- may need to start at higher cold inflation pressures because of the decreased pressure gain in autocrossing). Road: OE pressures Rain: For both autocross and road racing, you may have to increase tire pressure 6-10 psi from what you would normally run in dry conditions. Your car and driving style in the wet is important here, so some experimentation may be in order.
Care and Feeding ALIGNMENT Negative camber should be targeted between 1.5 to 3 degrees with a maximum of 4 degrees. Do not get too crazy here. TEMPERATURE The sweet spot of the tread compound is in the range of 160 - 220°F. Adjust the suspension settings of your car and the tire pressure in order to maximize performance. You know the drill: Experiment with one axle at the time. Do NOT change too many variables at one time.
Care and Feeding HEAT CYCLING (Primarily US Market): Heat cycled tires may come up to operating temperature slightly quicker than non-heat cycled tires, and on some cars we have noted a marginal improvement in lap times (maybe.1-.2 sec in a 38-40 sec autocross environment) and in tire wear. The improvement is not always obvious.
Care and Feeding SHAVING (Primarily US Market): Pilot Sport Cup starts life at 6/32nd of an inch (center tread depth) Michelin testing shows that a shaved tire at 3.5/32nds of an inch offers slightly more grip from the start of the competition life of the tire. Time differential between shaved/heat cycled @ and full tread depth/heat cycled is 0.5-0.6 seconds on a typical 35-38 sec autocross course. These are statistically-sound results; your results may vary.
Care and Feeding SHAVING (Primarily US Market): The consumer must decide if he/she is willing to give up 2.5/32nds of tread life and the cost of shaving in exchange for a potential 0.6 seconds – it depends on how serious you are about your time spent at the track. All things considered, the absolute quickest time will likely be achieved by shaving and heat cycling the Pilot Sport CUP.
You can recut Outside rib in zig-zag 5 mm wide and 4 mm deep 2nd and 3rd ribs lateral grooves, 7 mm wide and 5 mm deep DON ’T GET CARRIED AWAY! INSIDE RIB LATERAL GROOVE DO NOT RECUT THE CIRCUMFERENTIAL GROOVES Recutting To optimize deep water performance, you may recut Pilot Sport CUP in the following way: Care and Feeding
Currently available sizes in Pilot Sport CUP 205/50ZR15 (product number 87934) 225/50ZR15 (product number 88168 – launch April’03) 205/55ZR16 (product number 70213) 225/50ZR16 (product number 70436) 245/45ZR16 (product number 90104 – launch April’03) 205/50ZR17 (product number 93434) 225/45ZR17 (product number 77719) 255/40ZR17 (product number 61585) 225/40ZR18 (product number 87503) 265/35ZR18 (product number 60480) 285/30ZR18 (product number 81118 – launch April’03) 295/30ZR18 (product number 80852 – launch April’03) 315/30ZR18 (product number 86838 – launch May’03) 345/30ZR18 (product number 81504 – launch May’03)
Currently available sizes in Pilot Sport CUP What about tires for the 911 GT2? In 2003, we will offer a 315/30ZR18 for the rear axle of the GT2. However, an accompanying 235/40ZR18 for the front axle will not be availabvle until mid-year. The existing 225/40ZR18 has been found to work well on the GT2.
Michelin and PCA Go Racing Michelin as a sponsor of PCA Club Racing will support ten events in 2003. Trackside support Michelin ALMS engineers Fitting Services Tire Sales SebringCalifornia SpeedwaySummit Point Road AtlantaWatkins GlenCarolina Motorsport Park Lime RockPorsche Parade Mid OhioRoad America
Pressure Setting Guidelines for certain Porsche Tire/Vehicle Combinations
Stuff that a racer needs to think about... First of all, remember that the following recommendations are trends. Providing exact solutions is tough. Specific vehicle characteristics, wheel loads and/or driving styles have a big impact on the behavior of the tire/vehicle system.
Stuff that a racer needs to think about... Another thing to remember: Bigger isn’t always better, both in terms of ease of driving and in terms of lap times. If you take the time to look at the typical FIA GT or ALMS (prototype, GTS, or GT classes) tire/wheel combination, you will see that—even if the rules permit it—overly “fat” tires are rarely used.
Stuff that a racer needs to think about... Bigger isn’t always better, both in terms of ease of driving and in terms of lap times. Frequently, the tire looks “stretched out” on the application wheel, forming what looks to be a “trapezoidal” cross-section, with the tread width close to or less than the width of the tire’s beads. This is because of the simple fact that a “high-tension” tire shape is more efficient, in most cases, than a fat, “low-tension” shape.
Stuff that a racer needs to think about... What does this mean for you? Well, if you are confronted with the choice of squeezing a big tire onto its minimum recommended wheel width or stretching a smaller tire onto a relatively wide rim, you might want to pause for thought.
Stuff that a racer needs to think about... We have found the smaller-tire + wide-rim combination, with its accompanying “high-tension” inflated shape, can be more efficient: More direct yaw response Decreased “phase lag” between steering wheel input and vehicle turn-in Less “overshoot” at corner exit Less of a tendency to “wiggle” at corner exit (thus upsetting the car) when you roll back into the throttle Can result in decreased negative camber requirements, thus increasing braking and accelerating efficiency Can improve vehicle response to air pressure tuning
205/50-15 & 225/50-15 on older, lighter 911s Rear axle slip angle and cornering power: Little effect on rear axle slip angle from rear pressure, especially above 32-35psi hot Little to no effect on rear axle slip from front pressure changes Overall vehicle handling behavior and cornering attitude: Big effect from front pressure changes: at low g ’s (typically slow corners), higher = more understeer 30-35% decrease in gain between 26-38psi at high g ’s (typically faster corners), higher = less understeer 5-10% increase in gain between 26-38psi Little effect from rear pressure, especially above 32-35psi hot
205/50-15 & 225/50-15 on older, lighter 911s Overall Recommended Hot Pressures: Front: 32-35psi Rear: 32-35psi Driver/vehicle combo dictates the split!
205/55-16 & 225/50-16 on pre-964 and 964-chassis 911s Rear axle slip angle: Little effect on rear axle slip angle from rear pressure changes Little effect from front pressure changes at low g ’s (typically slow corners), but lower front pressure tends to be favorable at high g ’s Overall vehicle handling behavior and cornering attitude: Big effects from front pressure changes: low pressure favorable Steering gain decreases 25-30% between 26psi and 38psi In high-g corners (more tire load), required steering input decreases 20-25% Little effect from rear pressure changes Although the rear axle should still be looked at to adjust driver “feel”
205/55-16 & 225/50-16 on pre-964 and 964-chassis 911s Overall recommended hot pressure targets: Front: 26-28psi Rear: 32-35psi
225/50-16 & 245/45-16 on Porsche 944/944 Turbo Rear axle slip angle: Little effect on rear axle slip angle from rear pressure changes at low g ’s (typically slower corners). At high g ’s, decreasing the pressure will reduce the potential of the rear axle. Little effect on rear axle slip angle from front pressure changes (unlike for 911s!) Overall vehicle handling behavior and cornering attitude: Little effect from front pressure changes, except at high g’s A bit more effect from rear pressure changes, but the 944 chassis (in stock form) tends to “dampen” the effect of pressure changes Overall recommended hot pressure targets: Front: 35-38psi Rear: 26-30psi
225/40-18 & 265/35-18 on Porsche Boxster Rear axle slip angle: Decreasing the rear pressure will increase the potential of the rear axle Little effect on rear axle slip angle from front pressure changes Overall vehicle handling behavior and cornering attitude: Big effect from front pressure changes 20-25% decrease in steering gain (more understeer) between 26-38psi Big effect from rear pressure changes: increasing the pressure will tend to reduce the understeer Overall recommended hot pressures targets: Front: 32-34psi Rear: 36-39psi
225/40-18 & 285/30-18 on Porsche 996 Rear axle slip angle: Decreasing the rear pressure will increase the potential of the rear axle Little effect on rear axle slip angle from front pressure changes Overall vehicle handling behavior and cornering attitude: Big effect from front pressure changes Steering gain decreases 20-25% between 26-38psi Small effect from rear pressure changes: increasing the pressure will tend to reduce the understeer slightly Ov erall recommended hot pressure targets: Front: 32-34psi Rear: 37-40psi
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