How Michelin's S5 Tires Make the Staggering Porsche 911 GT3 RS Go Fast Year-Round

Porsche’s GT division boss Andy Preuninger had a problem. Some of his most enthusiastic 911 GT3 RS customers complained they couldn’t get to spend enough real-world time behind the wheel of their snarling near-race-car-level monsters. The Michelin Cup 2 tires fitted as standard equipment on the GT3 RS—ultra-high-performance tires designed to deliver maximum grip on dry tarmac in ambient temperatures between 60 and 90 degrees Fahrenheit—made the car extremely tricky to drive in cold and/or damp conditions.  

What to Do?

There was only one solution. A phone call to Michelin kicked off a project to develop a tire that could broaden the GT3 RS’ operational envelope. The result is the Michelin Pilot Sport S5.  

“We are responding to demand from our particularly performance-focused customers that have expressed a desire to spend more time on track during spring and autumn,” said Preuninger, the man who knows more about building factory-fast 911s than anyone on the planet. So Porsche and Michelin invited us to the French tiremaker’s sprawling R&D complex at Ladoux, just outside Clermont Ferrand, to put the new Pilot Sport S5 tire to the test. 

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What’s New

The new Michelin Pilot Sport S5s are the same size as the original equipment Cup 2s, 275/35 ZR20 for the front wheels and 335/30 ZR21 at the rear, which makes the rear tire the largest Pilot Sport S5 Michelin produces. The tire casing’s design and structure are very close to those of the Cup 2, according to Bertrand Fraenkel, the super-sport tire development leader at Michelin. “We [still] needed to have the tire work like a Cup 2,” he said.  

What’s different here is the tread pattern, which features four large central grooves 0.3 inch deep rather than the Cup 2’s shallower three offset grooves, and the rubber compound, which features a high silica-content wet-weather compound across the center of the tire combined with a dry-weather compound on the shoulders.  

“The Pilot Sport S5 gets up to temperature very quickly,” said Jörg Bergmeister, the former racing driver who now does a lot of development driving for Porsche. That’s so it will work on cold or wet roads, but Bergmeister says testing at the Nürburgring and Portugal’s fast Portimão circuit in ambient temperatures of 68 degrees or more has proven the tire also delivers a high level of performance outside its core operating window. The Pilot Sport S5 also meets all legal requirements in terms of rolling resistance and noise levels and offers higher wear resistance than the Cup 2. Indeed, Fraenkel says the Pilot Sport S5 will likely last twice as long as a Cup 2 before needing to be replaced, in part because of its compound, and in part because its tread is 30 percent deeper.  

The mission was to develop a tire that would allow Porsche 911 GT3 RS owners to drive their cars with confidence in ambient temperatures up to 20 degrees cooler than the bottom end of the Cup 2’s comfort zone, and on wet roads. And after back-to-back testing of 911 GT3 RS models equipped with the Pilot Sport S5 (the red car in the photos) and the Cup 2 (the yellow car), we can say, “Mission accomplished.” The Pilot Sport S5 transforms the race-face GT3 RS from a hardcore track rat into a daily driver. Well, almost. It’s still very fast, very loud, and very stiff. But Preuninger’s hardcore enthusiasts will indeed be able to drive their cars more often.  

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Wet Matters

Our test drive, with Michelin’s super-sport tire development and test driver, Jérôme Haslin, running lead in a Pilot Sport S5–equipped silver GT3 RS, started on a wet handling track, a sinuous 1.7-mile circuit with a water system that keeps it streaming wet; wet enough, in fact, that we were warned to be careful with throttle on the one long straight as the Cup 2–equipped GT3 RS would start hydroplaning at 75 mph and could snap sideways and spin. We set both cars in Track mode, and both had their suspension, e-differential, stability control, and traction control switched to the same settings. The Cup 2s were set at 30 psi up front and 32 psi at the rear, while the Pilot Sport S5s ran at 35 psi and 38 psi, respectively.  

The difference between the two tires was stunning. The GT3 RS on Cup 2s felt like you were driving on ice. There was virtually no grip, no sense of the adhesion limits front or rear. Trying to get the Porsche around the soaking-wet track at any sort of pace was like waltzing an angry lion around a hockey rink. So it was fingertips on the steering wheel and feather feet on the pedals as we tried to keep what is one of the quickest street-legal cars in the world on the soaked tarmac at speeds that wouldn’t stir a highway patrol officer from his coffee and doughnut.  

On the Pilot Sport S5s, the GT3 RS felt properly connected to the road. Sure, all that water meant it wasn’t difficult to get the Porsche to slide, at either end of its chassis, but there was substantially more grip. More important, you can feel what is happening at the contact patch of the tires, feel the forces build through your hands and the seat of your pants. You can lean on the front axle, you can get power to the rear wheels, you can get the car to change direction. And when the tires reach the adhesion limit, the transition to a slide is much more benign and more controllable. The new Michelins make the GT3 RS much more confidence inspiring when you pick up the pace. Bergmeister says that on the Pilot Sport S5, the GT3 RS is 10 seconds quicker around this 1.7-mile wet track than it is on Cup 2s, a huge performance advantage. And no question, you can feel it. 

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What About the Dry?

To prove the Pilot Sport S5 isn’t a one-trick pony, Haslin then took us to Michelin’s Track 3, a dry handling track that’s a fast, sweeping ribbon of road stacked with awkwardly long corners and a couple of sharp flick-flaks. It’s a track that works the front tires hard on corner entry and the rear tires hard almost everywhere else. This was where we could really wind out the 911 GT3 RS, though with damp grass right at the edge of the circuit, you didn’t want to drop a wheel off the hard stuff. 

On the Cup 2s the GT3 RS felt crisper and more immediate when pushed, and it seemed to be more consistent over the entirety of our four-lap run. The car on the Pilot Sport S5s felt a little more relaxed from the outset, more measured in its transitions. You can feel, as the tire heats up, the car beginning to move around as if the contact patch is getting a little greasy, but it isn’t unpleasant or scary. The GT3 RS’ fundamental characteristics remain unchanged. Indeed, the S5 feels like it does the same things as the Cup 2s, just in a slightly more deliberate manner. 

Bottom line: On a dry track and in warmer ambient temperatures, the Cup 2 is the quicker tire, and for longer. But the Pilot Sport S5 is a remarkably polished all-rounder, unquestionably the better tire for enthusiasts who want to drive their GT3 RS in almost a much broader range of weather. More important, our session in the Porsches at Michelin revealed a wider truth that holds even for enthusiasts like us who don’t have the budget to buy a 911 GT3 RS: Fitting the right tire is absolutely the most cost-effective way of improving your car’s performance, both on the road and on the track. 

The Porsche 911 GT3 RS-spec Pilot Sport S5 will be available in the U.S. through Tire Rack. And if you own a regular 911 GT3 you want to drive most of the year, don’t fret: Porsche is considering developing a similar Pilot Sport S5 for that car, too.