Michelin, tires, Power RS

Michelin Power RS Motorcycle Tire Review

New sportbike tire impresses at the Losail International Circuit

Losail International Circuit is big, fast, and bounded by desert—even a gentle breeze leaves behind a fine layer of dust. It's an unlikely venue to launch a street tire, yet Michelin nevertheless brought a load of media to Doha to experience the new DOT-approved Power RS motorcycle tire at night under bright-as-day floodlights for maximum effect.

"It's kind of like riding on rain tires on a dry track," explained Ben Spies, who won two World Superbike races at the Qatari racetrack. "You have grip, but the tires are flexing under you. It's a strange, vague feeling." Spies' words were ringing in my ears as I raced toward Turn 1 behind a Michelin test rider and a long string of journalists.

Bookended by the competition-ready Power Slick Evo and touring-oriented Pilot Road 4, the Power RS—which replaces both the Power 3 and SuperSport Evo—is available in 13 sizes (four fronts, nine rears) to cover everything from sporty entry-level singles to fire-breathing superbikes and even fat-tired sport cruisers like the Ducati Diavel.

Michelin VP of Worldwide 2-Wheel Sales David Jean set the tone for what company president Gary Guthrie called a "watershed moment." Through a thick French accent, Jean said, "When it comes to dry-weather grip, when it comes to agility, when it comes to stability, the Power RS exceeds everything that is currently available on the market."

Superlatives are easier to swallow when the source has a history of innovation. Semi-slick tread, silica, and dual/asymmetric compounds all originated with Michelin. Jean compared the latest advancement, Adaptive Casing Technology (ACT+), to the most significant development to come out of Clermont-Ferrand, the radial tire.

Michelin tire test at Losail Circuit
For the Power RS introduction, Michelin sourced liter-class sportbikes from Aprilia, BMW, Ducati, Honda, Kawasaki, and Yamaha. Most riding was done under the exceptional floodlight system, installed in 2007 by US firm Musco Lighting.Photo: Michelin

ACT+ features a single, variable-angle casing ply, the angle of which in the crown is close to 90 degrees to maximize flexibility and straight-line stability at high speeds. Meanwhile, the upper portion of the ply is folded back over itself at the shoulder to increase rigidity for enhanced cornering stability.

“With the lights, it’s strange. You’re going 200 mph when you hit the brakes for Turn 1, and your shadow flies past you.”

For additional insight, I phoned my longtime Bonnier Motorcycle Group co-worker, Cycle World Technical Editor Kevin Cameron. In the past, he explained, a single radial ply has been used, with the sidewalls optionally stiffened by "chafers"—extra plies wrapped around the beads and rising up the sidewalls.

360 view of the new Michelin Power RS tire
Michelin Power RSAnimated GIF: Michelin

One or more belt plies are then applied under the tread—not at all flexible from side-to-side but very flexible in bending. Michelin has altered the angle of the ply, so when that ply is wrapped around the beads and continues up the sidewall to the shoulder on either side, it is at a bias angle to the rest of the single main ply.

This gives the desired strength, and stiffness can be altered by varying the thickness of rubber between the single main ply and itself when folded up over the beads. It also reduces the parts count and is strong because all fibers of single main ply and its folded-up sidewall stiffening are continuous.

Like Pilot Power 3, the Power RS uses two compounds, with a harder, silica-rich crown (68 percent front, 54 rear) and softer carbon-black shoulders (16 percent front, 23 rear). Dry and wet grip are maximized via high-tech elastomers. Compounds developed for the new range employ the latest styrene-butadiene rubber (SBR) polymers.

“Modern compounding technology—the one that caused former Dunlop engineer Dave Watkins to say compounding had shifted from being mixtures to dependent upon chemical reactions—is based on adding ‘functional groups’ to the ends of rubber chains,” said Kevin.

“These groups are capable of forming actual chemical bonds with appropriately primered silica particles, not merely being vaguely attracted to them as rubber is to carbon black particles. The ‘vague attraction’ is given the term, ‘short-range forces’ or ‘van der Waals forces.’”

When strong chemical bonds are formed between rubber chains and silica particles, tire tread compound becomes a composite material, consisting of a strong network of a few bonded-to-silica rubber chains in a soft matrix of unbonded chains. This explains how Michelin can legitimately claim exceptional grip and durability.

All this is possible thanks a 700-million-euro investment that Michelin recently made in research and development. The company develops its own materials while also benefitting from the extensive production capacity brought about by corporate interests that extend far beyond motorcycles.

Michelin Power RS review
Several waves of journalists from all over the world were treated to detailed overviews of the new Power RS along with a series of on- and off-bike workshops.Photo: Michelin

Externally, the Power RS resembles street-legal race rubber, with short grooves strategically cut in the otherwise smooth tread for maximum water evacuation at moderately aggressive lean angles. “It’s not a track tire,” said Pierre-Yves Formagne, head of sport/touring development. “It’s a road tire you can use on the track.”

Constructed in 2004 at a cost of more than $50 million, Losail is wide and flat, with a 3.34-mile mix of lefts and rights capped with a half-mile-plus-long front straightaway where a few days earlier MotoGP bikes had topped 210 mph. First order of business was three reference laps on the Pilot Power 3 followed by three more on the Power RS.

Spies, who raced both Yamaha and Ducati factory bikes at Losail, told me about his first MotoGP test under the lights in 2010. “I had done a 24-hour endurance race, so I knew what it was like to ride in the dark,” he said. “With the lights, it’s strange. You’re going 200 mph when you hit the brakes for Turn 1, and your shadow flies past you.”

Michelin Power RS comparison
This graphic clearly shows Michelin’s claims for the improved performance offered by the Power RS versus its own Power 3 and Power Supersport Evo.Photo: Michelin

That image was fresh in my mind as the sun went down and the nearly 4,000 lights surrounding the circuit came up. Michelin somehow wrangled an impressive mix of liter-class European and Japanese sportbikes for journalists to ride; I opted for the most commonly represented of those many machines, a BMW S1000RR.

Unlike other writers in attendance, I had never lapped Losail. In fact, I had never even traveled to that part of the planet. “This track is very, very fast—probably one of the most difficult tracks in the world on tires,” Formagne said. “You will see that the Power RS is very good on this very difficult track.”

Michelin Power RS wet grip lean angle
At Losail, Michelin focused primarily on dry-weather grip, stability, and agility, but wet-weather traction was also given high priority in the development of the new Power RS.Photo: Michelin

Chalk it up to nervousness, but the Power RS felt grippier and more confidence-inspiring than the Pilot Power 3. Michelin claims that a test rider on an S1000RR shod with Power RS tires was 3.5 seconds quicker per lap at the 2.17-mile Circuit of Cartagena in Murcia, Spain. That’s a lot of time on a short track with 18 turns.

After the initial runs, we moved to a miniature version of the Losail circuit for a chance to spin three laps on what was clearly a very dusty surface capped with a short well-watered braking zone. “We haven’t swept the track since Monday—three days ago,” admitted one of the test riders. “Initially, we were worried, but grip is good.”

Waiting my turn, I watched others lean over far enough to drag their knees as well as the under carriages of the single–cylinder KTM and Kawasaki. In fact, just one rider got sufficiently overzealous with the throttle to generate a visible rear-tire slide. Likewise, the wet braking section presented no drama whatsoever.

After dinner, we returned to the big track for three 20-minute sessions. Slowly but surely (emphasis on slowly), I got more familiar with the layout. Appearing suddenly in the dark recesses of my rear-view mirrors, one of the Michelin test riders passed me and pointed to the tailsection of his BMW—the international sign for “follow me.”

Faster and faster we went, until he finally had enough and streaked off into the distance. I’ve always felt most comfortable in left-hand corners (must be an American thing, dirt-track and all), but my favorite corners were a tricky series of rights—Turns 4 and 5, 7, and 12, 13, and 14. The third and final session ended too soon.

Last September at the Red Bull Ring in Austria, I interviewed Michelin Racing Technical Director Nicolas Goubert, who emphasized during our conversation that the French company’s participation in any form of racing, including MotoGP, only makes sense if it is able to learn something that directly relates to consumers.

“Our big boss always tells us, ‘You should not be working on something that I will not see in the future in our customer product,” he said. “If you are, please stop. We are not here for that.’” Which is why, Goubert explained, that moving from 16.5-inch sizing to the current 17s was such a critical part of negotiations with series rights-holder Dorna.

“Being able to work on the ‘normal’ wheel size is important because technology transfer will be easier,” he added. “We’ve been trying to start in Formula 1, but we’re not interested in working with 13-inch tires—not even the cheapest car in the world uses 13-inch tires.”

While a spokesperson denied that the Power RS is directly related to any of the tires the company is currently supplying to MotoGP riders, Michelin has nevertheless developed an exceptional product to meet the needs of street riders and maybe even track-day riders. For proof, all you need is a light dusting of desert sand.